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Research Article Experimental Study and Numerical Simulation of Dynamic Stress-Strain of Directional Blasting with Water Jet Assistance Dengfeng Su , 1 Dandan Zheng, 2 and Lingang Zhao 1 1 School of Environment and Resource, Southwest University of Science and Technology, Mianyang 621010, China 2 Dazhou Administration of Work Safety, Dazhou 635000, China CorrespondenceshouldbeaddressedtoDengfengSu;[email protected] Received 2 November 2018; Revised 7 January 2019; Accepted 19 February 2019; Published 24 March 2019 AcademicEditor:AdamGlowacz Copyright©2019DengfengSuetal.isisanopenaccessarticledistributedundertheCreativeCommonsAttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Effective control of the explosive energy and the propagation direction of blast-induced crack and minimizing damage of remainingrockmassarethemainpurposesofdirectional-controlledblasting.Inthispaper,theexperimentaltestonblaststrain fieldsaffectedbywaterjetslotandblastholewallprotectionmaterialisconducted.Next,theFEMsoftwareANSYS/LSDYNAis usedtosimulatetheblast-inducedcrackpropagationandtheblaststresswavetransmissionofdifferenttypesofblasthole,andthe distribution and evolution law of dynamic blast stress are also analyzed. e results indicate that the existence of blasthole wall protection material is not only beneficial to the “guiding effect” of blast-induced crack propagation of water jet slot but also beneficialtoreduceblast-induceddamageofremainingrockmass.Besides,thebigger D m /r b is,theweakerthe“guidingeffect”and “blasthole wall protection effect” by water jet slot and wall protection material are. 1.Introduction In China, drill-blasting method is the most cost-effective wayintheconstructionofundergroundspaceengineering. However,ithasmanydisadvantages,whichproducessome random radial fractures from a blasthole along the un- specific directions and invites overbreaks among the rock masses with low strength or with a number of cracks, posingaseriousthreattolong-termstabilityofpermanent structures including underground nuclear waste re- positories and open-pit slopes [1]. To solve the disadvan- tages of the traditional drill-blasting method, directional control blasting technology was put forward, and its main purposeiseffectivecontroloftheexplosiveenergyandthe propagationdirectionoftheblast-inducedcrack[2,3].e most direct ways to guide crack growth along the specific direction and inhibit crack growth along other directions are to make notches by using grooving machine along the desireddirectiononthesurfaceoftheboreholewall[4–6]. Based on this idea, several researchers [7–10] have done many researches for guiding crack propagation and min- imizing rock damage in the undesired directions so as to achieve better performance of fracture plane control, and many works investigated the notched borehole blasting technique with different solutions. Katsuyama et al. [11] suggestedacontrolledblastingmethodusingasleevewith slits in a borehole. Fourney et al. [12, 13] conducted controlledblastingexperimentswithanotchedboreholein PMMAspecimens,whichdemonstratedthatblast-induced crack propagated along the notched direction under the blast loading. Mohanty [14, 15] suggested a fracture plane controltechniqueusingsatelliteholesoneithersideofthe centralpressurizedholeanddemonstrateditsusethrough laboratoryexperimentsandfieldtestsinrock.Duetal.[16] studied the mechanical effect of the V-shape notched borehole under the blast loading, and the control mech- anism of the notch to rock-oriented cracking is demon- strated,andthecriterionfortheadvanceoninitialcrackin notched borehole blasting is established. Zong [17, 18] analyzed the beginning and end condition as well as the developing direction, speed, and length when decoupling chargeisadoptedforsymmetricgroovedholewellbasedon the theory of rock fracture mechanics and function of explosiongas.Choetal.[19]proposedadynamicfracture process analysis based on the dynamic finite element method and fracture mechanics to verify the dynamic Hindawi Shock and Vibration Volume 2019, Article ID 1659175, 15 pages https://doi.org/10.1155/2019/1659175
Transcript
Page 1: ExperimentalStudyandNumericalSimulationofDynamic Stress ...downloads.hindawi.com/journals/sv/2019/1659175.pdf,kLL jLL xLL L xLL jLL,kLL L L©L, L©Lk L©Lff L©Lx _NF ig E NFE #_#YNIkff©,Ifiig

Research ArticleExperimental Study and Numerical Simulation of DynamicStress-Strain of Directional Blasting with Water Jet Assistance

Dengfeng Su 1 Dandan Zheng2 and Lingang Zhao1

1School of Environment and Resource Southwest University of Science and Technology Mianyang 621010 China2Dazhou Administration of Work Safety Dazhou 635000 China

Correspondence should be addressed to Dengfeng Su dengfengcqu163com

Received 2 November 2018 Revised 7 January 2019 Accepted 19 February 2019 Published 24 March 2019

Academic Editor Adam Glowacz

Copyright copy 2019 Dengfeng Su et al is is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Effective control of the explosive energy and the propagation direction of blast-induced crack and minimizing damage ofremaining rock mass are the main purposes of directional-controlled blasting In this paper the experimental test on blast strainfields affected by water jet slot and blasthole wall protection material is conducted Next the FEM software ANSYSLSDYNA isused to simulate the blast-induced crack propagation and the blast stress wave transmission of different types of blasthole and thedistribution and evolution law of dynamic blast stress are also analyzed e results indicate that the existence of blasthole wallprotection material is not only beneficial to the ldquoguiding effectrdquo of blast-induced crack propagation of water jet slot but alsobeneficial to reduce blast-induced damage of remaining rockmass Besides the biggerDmrb is the weaker the ldquoguiding effectrdquo andldquoblasthole wall protection effectrdquo by water jet slot and wall protection material are

1 Introduction

In China drill-blasting method is the most cost-effectiveway in the construction of underground space engineeringHowever it has many disadvantages which produces somerandom radial fractures from a blasthole along the un-specific directions and invites overbreaks among the rockmasses with low strength or with a number of cracksposing a serious threat to long-term stability of permanentstructures including underground nuclear waste re-positories and open-pit slopes [1] To solve the disadvan-tages of the traditional drill-blasting method directionalcontrol blasting technology was put forward and its mainpurpose is effective control of the explosive energy and thepropagation direction of the blast-induced crack [2 3] emost direct ways to guide crack growth along the specificdirection and inhibit crack growth along other directionsare to make notches by using grooving machine along thedesired direction on the surface of the borehole wall [4ndash6]Based on this idea several researchers [7ndash10] have donemany researches for guiding crack propagation and min-imizing rock damage in the undesired directions so as toachieve better performance of fracture plane control and

many works investigated the notched borehole blastingtechnique with different solutions Katsuyama et al [11]suggested a controlled blasting method using a sleeve withslits in a borehole Fourney et al [12 13] conductedcontrolled blasting experiments with a notched borehole inPMMA specimens which demonstrated that blast-inducedcrack propagated along the notched direction under theblast loading Mohanty [14 15] suggested a fracture planecontrol technique using satellite holes on either side of thecentral pressurized hole and demonstrated its use throughlaboratory experiments and field tests in rock Du et al [16]studied the mechanical effect of the V-shape notchedborehole under the blast loading and the control mech-anism of the notch to rock-oriented cracking is demon-strated and the criterion for the advance on initial crack innotched borehole blasting is established Zong [17 18]analyzed the beginning and end condition as well as thedeveloping direction speed and length when decouplingcharge is adopted for symmetric grooved hole well based onthe theory of rock fracture mechanics and function ofexplosion gas Cho et al [19] proposed a dynamic fractureprocess analysis based on the dynamic finite elementmethod and fracture mechanics to verify the dynamic

HindawiShock and VibrationVolume 2019 Article ID 1659175 15 pageshttpsdoiorg10115520191659175

fracture and fragmentation mechanism due solely to thestress wave in blasting Zhang [20] simulated the stressdistribution law by ANSYSLS-DYNA and the dynamicseam forming mechanism is also analyzed based on thefracture mechanics theory Yang et al [21 22] studied thecrack propagation and changes in stress intensity at thecrack tips of the two V-notched borehole by the blastloading system using dynamic reflected caustics e ex-perimental results show that the crack tips do not meetdirectly but are deflected and become anisotropic and thecrack propagation velocity first decreases oscillates andthen gradually increases to peak followed by a decreaseuntil the oscillations stop Yue et al [23 24] conductedmodel experiments to investigate the influence of emptyholes with different shapes on directional fracture-controlled blasting of rock by using new digital laser dy-namic caustics e results show that the preset rhombichole can achieve fine directional fracture-controlledblasting and effectively ensure the forming effect ofblasting around the roadway Chen et al [25] analyzed themechanism of rock fracturing between holes in deep-holepresplit blasting and the crack evolution under the syn-ergistic action of dynamic and static loads and the scope ofstress-induced cracks around blastholes and the maximumlength of secondary cracks induced by detonation gas werecalculated Zhu and Xu [26] compared the stress anddamage distribution of conventional circle hole and notchhole by implementing a user-defined statistical damagemodel based on the secondary development of the LS-DYNA and the results demonstrate that two mechanicaleffects are induced by the notch and high stress concen-tration is generated at the edge of the notch and the stress atthe other part of blasthole is reduced

Above research studies concentrate mainly on theV-notch directional blasting technology with mechanicalgrooving tool assistance and demonstrate that this method issuperior to the traditional blasting technology to control thedirection of blast-induced crack propagation However thismethod has a disadvantage of notching tool to be stuck andwear and tear especially for the soft surrounding rockblasting In order to solve this problem the unique characterfor low damage directional control cutting and highlyenergy accumulation of water jet attracted the attention ofresearchers (Figure 1) [27 28] and then the directional-controlled blasting with water jet assistance was put forward[29ndash32] Its mechanism was analyzed and the blast-inducedcrack initiation criterion along the direction of the water jetslot under blast loading was established Furthermore theeffect of water jet slot for reducing blast-induced groundvibration in tunnel excavation was analyzed by Kim andSong [30] and the nonlinear hydrokinetics code (AUTO-DYNA) was used to simulate the effect of reduction of blast-induced vibrations by abrasive water jet cutting

Based on above studies an attempt was made in thispaper to study the dynamic evolution law of blasting strainunder different conditions An experiment was performed toinvestigate the evolution law of dynamic strain of differentmodels en numerical simulation for the transmissionand reflection of blast stress wave and the propagation law of

blast-induced crack were performed by using the FEMsoftware ANSYSLS-DYNA

2 Experimental Test on DynamicBlasting Strain

21 Test Instrument and Test Principle Blast stress wave hasthe characteristics of wide band high upper limit frequencyand large amplitude change so the test instrument musthave a high sampling frequency In this paper a multi-channel dynamic analysis signal testing system produced byDonghua Testing Technology Co Ltd was applied itcomprises an ultrahigh dynamic strain meter with eightchannels a blast loading system and a computer used tocollect blasting data the connection of the test system isshown in Figure 2 and the procedure of experimental test isshown in Figure 3

PMMA was used in these blast tests in that it almostshares similar fracture behaviors with brittle rock underdynamic conditions [33] PMMA specimens were 300mmtimes 300 mmtimes 2 mm in size and its parameters are shownin Table 1 A blasthole was placed in the center of thespecimen with the center of the blasthole 150mm from thefour sides All the blastholes are 3mm in radius

In order to investigate dynamic strain law underdifferent blasting conditions three shapes of blastholeswere designed 1 test model has one regular blasthole 2test model has one blasthole with two water jet slot alongthe horizontal axis and 3 test model has one water jetslotted blasthole with the blasthole wall protection ma-terial mounted on the two opposite surfaces of theblasthole PVC material was used as the wall-protectedmaterial Each test model and its strain gauge arrange-ment are shown in Figure 4 In addition each blastholewas charged by 40mg explosive which was made ofpropellant and the spark starter was used as a detonatingdevice

22 Experimental Results Analysis Table 2 and Figures 5ndash7present different types of strain values under three differentblasting models respectively For 1 test model mean strainpeak value (PSPV) at E1-1 test point is very close to thePSPV at E1-3 test point and the mean strain peak value atfour test points is close to the same In addition the strainwave evolution law of E1-1 test point is almost the same asthat of E1-3 test point and so as to E1-2 test point and

Water jet slot

Pump pressure 20MPa

Figure 1 Coal and rock mass cutting using water-only jet

2 Shock and Vibration

E1-4 test point which shows that when the explosive ex-plodes in a regular blasthole the blasting load almost evenlyworks on the circular blasthole surface [34]

By comparing Figure 5 with Figure 6 we can see that thePSPV value at E2-1 test point is 3667 greater than PSPVat E1-1 test point and the PSPV at E2-2 test point is 179greater than the PSPV at E1-2 test pointat is because thewater jet slot results in stress concentrations along the di-rection of the water jet slot while detonation gases work on

the blasthole surface or stress waves arrive at the tip of thewater jet slot during blasting In addition the positive strainpeak value (PSPV) and mean strain peak value (MSPV) atE1-3 test point and E1-4 test point are almost the same asthe PSPV and MSPV at E2-3 test point and E2-4 testpoint and so as to the evolution law of explosive strainwave It can be seen from the above analysis that the waterjet slot changed the law of stress field distribution duringthe blasting which results in the stress concentrations

Experimental testspecimens

Strain-compensated

Ultra dynamic strainmeasuring systemSignal sensor Data processing

system

Front view

Back view

Figure 2 Diagram of test system connection

If the installation of signal sensor is

properNo

Yes

Installingthe experimental

test specimens

Charging and connecting the

test circuit

Starting the ultra dynamic strain

measuring system

If the connection of test circuit is

proper

Detonating explosive

No

Yes

Test data processing and

analysis

Replace the signal sensor

Replace the test circuit

Figure 3 Diagram of experimental test procedure

Table 1 Parameters of PMMA

Density (gcm3) Poisson ratio Elastic modulus (GPa) Longitudinal wave velocity (cmμs) Shear wave speed (cmμs)12 031 61 23times105 126times107

Shock and Vibration 3

along the direction of the water jet slot However in thedirection perpendicular to water jet slot the existence ofwater jet slot has hardly changed the distribution of stressfield

For 3 test model the existence of blasthole protectionmaterial has greatly changed the distribution law and evo-lution law of the explosive strain wave On one hand thePSPV in the direction of the water jet slot gradually in-creases the PSPV at E2-1 test point is 3667 greater thanthe PSPV at E1-1 test point the PSPV at E3-1 test point is3537 greater than PSPV at E2-1 test point and the PSPVat E3-1 test point is 8500 greater than the PSPV at E1-1test point On the other hand the blasting strain values in thedirection perpendicular to water jet slot respectively de-crease to smaller values Just in regard to the PSPV the figure(623167 με) at E2-3 test point sees a 437 decrease endingup with 350768 με at E3-3 test point and the figures at E2-4 test point and E3-4 test point almost share the samedecreasing proportion It is suggested that in contrast withdirectional-controlled blasting with water jet assistance theexistence of blasthole wall protection material can sharplyreduce the energy of stress wave working on the remainingsides so as to achieve the purpose of protecting the sur-rounding rock

Furthermore by comparing the blasting strain of 2 testmodel and 3 test model we can see that in the direction ofwater jet slot the blast strain is much greater than that in the

direction perpendicular to water jet slot For 2 test modelthe PSPV at E2-1 test point sees a 2836 decrease from869829 με reaching 623167 με at E2-3 test point Besidesfor 3 test model compared with PSPV (1177456 με) at E3-1 test point the PSPV at E3-3 test point falls by 7021ending at 350768 με Both the two decreasing trendsdemonstrate that water jet slot can have an obvious effect onstress concentration along the direction of water jet slot so asto more easily generate perforative fractures along this di-rection during blasting and the remaining rock can be betterprotected

To sum up some conclusions can be summarized fromthe experimental test as follows

(1) Under the combined effect of blasthole wall pro-tection material and water jet slot the PSPV bycomparing with regular blasthole blasting was in-creased by 8500 in the direction of water jet slotand the PSPV in the direction perpendicular to thedirection of water jet slot was reduced by 7021

(2) In contrast with directional-controlled blasting withwater jet assistance the existence of blasthole wallprotection material is not only beneficial to theldquoguiding effectrdquo of blast-induced crack propagationof water jet slot but also beneficial to reduce blast-induced damage of remaining rock mass

Regular blasthole

2

E1-4

E1-3

E1-1 E1-24

(a)

Water jet slotted blasthole

2

E2-1 E2-24

E2-4

E2-3

(b)

Water jet slotted blastholewith wall protection material

E3-4

E3-3

2

E3-1 E3-2

4

(c)

Figure 4 Sketches of three different blasting models and the strain gauge arrangement (a) 1 test model (b) 2 test model and (c) 3 testmodel

Table 2 Strain values for three different blasting models

Test model Strain valueValues (με)

Channel 1 Channel 2 Channel 3 Channel 4

Model 1Positive strain peak value 636454 537698 672342 570690Negative strain peak value minus495945 minus248893 minus722151 minus396569Mean strain peak value 83223 73074 92998 78041

Model 2Positive strain peak value 869829 633962 623167 520278Negative strain peak value minus341492 minus280124 minus718531 minus388996Mean strain peak value 171153 132421 80121 63676

Model 3Positive strain peak value 1177456 810468 350768 295034Negative strain peak value minus772859 minus348843 minus368530 minus271644Mean strain peak value 224876 189897 27480 12654

4 Shock and Vibration

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 636454μεNSPV ndash495945μεMSPV 83223με

(a)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 537698μεNSPV ndash248893μεMSPV 73074με

(b)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 672342μεNSPV ndash722151μεMSPV 92998με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 570690μεNSPV ndash396569μεMSPV 78041με

(d)

Figure 5 Waveform curve of dynamic strain for 1 test model (a) E1-1 test point (b) E1-2 test point (c) E1-3 test point and (d) E1-4test point

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 869829μεNSPV ndash341492μεMSPV 171153με

(a)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 633962μεNSPV ndash280124μεMSPV 132421με

(b)

Figure 6 Continued

Shock and Vibration 5

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 623167μεNSPV ndash718531μεMSPV 80121με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 520278μεNSPV ndash388996μεMSPV 63676με

(d)

Figure 6 Waveform curve of dynamic strain for 2 test model (a) E2-1 test point (b) E2-2 test point (c) E2-3 test point and (d) E2-4test point

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 1177456μεNSPV ndash772859μεMSPV 224876με

(a)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 810468μεNSPV ndash348843μεMSPV 189897με

(b)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 350768μεNSPV ndash368530μεMSPV 27480με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 295034μεNSPV ndash271644μεMSPV 12654με

(d)

Figure 7 Waveform curve of dynamic strain for 3 test model (a) E3-1 test point (b) E3-2 test point (c) E3-3 test point and (d) E3-4test point

6 Shock and Vibration

3 Numerical Simulation of BlastStress Evolution

e FEM software ANSYSLS-DYNA and the post-processing software LS-PREPOST were applied to in-vestigate the blasting stress wave evolution law and the blast-induced crack propagation law for different conditions

31 Numerical Simulation Model ree simulation caseswere conducted by ANSYSLS-DYNA Due to the symmetryof the simulated object both simulation cases applied aquasi-2D simulation model For each case the size of rock is150 cmtimes 150 cmtimes 03 cm the diameter of blasthole is 5 cmthe thickness of the blasthole wall protection material is05 cm and the size of the water jet slot is25 cmtimes 05 cmtimes 03 cm e 3 simulation model is shownin Figure 8

32 Material Model

321 Rock Material type 3 of LS-DYNA (lowastMAT_PLASTIC_KINEMATIC) was applied to model the rock [35] and itsparameters are shown in Table 3

322 BlastholeWall ProtectionMaterial Material type 3 ofLS-DYNA (lowastMAT_PLASTIC_KINEMATIC) was applied tomodel the blasthole wall protection material [35] and itsparameters are shown in Table 4

323 Explosive Material type 8 of LS-DYNA(lowastMAT_HIGH_EXPLOSIVE_BURN) was chosen as theexplosive model and the pressure released by the chemicalenergy in the engineering calculations was modelled by theJonesndashWilkinsndashLee equation of state e JWL EOS can bewritten in the following form [35]

Pe A 1minusω

R1V1113888 1113889e

minusR1V+ B 1minus

ωR2V

1113888 1113889eminusR2V

+ωEe

V (1)

where Pe is the pressure produced by the detonationproducts from explosive where ω A B R1 and R2 are user-defined input parameters V is the relative volume and Ee isthe internal energy per initial volume as shown in Table 5

324 Air Air was modelled by the material type 9 of LS-DYNA (lowastMAT_NULL) with the Gruneisen equation epressure Pa can be calculated by [35]

Pa C0 + C1μ + C2μ2 + C3μ3 + C4 + C5μ + C6μ2( 1113857Ea

μ 1

Vaminus 1

⎧⎪⎪⎪⎪⎨

⎪⎪⎪⎪⎩

(2)

where C0 C1 C2 C3 C4 C5 and C6 are user-definedconstants ρa is the density of air Va is the relative

volume of air Ea is the internal energy of air as shown inTable 6

33 Numerical Calculation Algorithm Lagrange algorithmhas the priority of less computation time and accuratelydescribing the boundary movement of structure so it isalways used to analyze the explosive detonation Howeverit has a big disadvantage of causing element distortion andeven leads to the termination of calculation when dealingwith the large deformation numerical calculation Inorder to avoid the above problem fluid-solid couplingalgorithm was adopted for the analysis of the explosivedetonation of which ALE algorithm was used for ex-plosive and air and Lagrange algorithm for rock andprotecting pipe e material derivative equation and thegoverning equations of the ALE algorithm can beexpressed as follows [35]

df(X t)

dt

zf(ξ t)

zt+ vi minuswi( 1113857

zf(x t)

zxi

zρzt

ρzυi

zx+ ωi

zρzx

ρzυi

zt+ ρωi

zυi

zxj

zσij

zxj

+ ρfi

ρze

zt σij

zυi

zxj

minuszq

zxj

minus ρωi

ze

zxi

(3)

where f is the physical quantity vi is the velocity of particleX ωi is the velocity of the computational grid xi is theLagrangian coordinate system yi is the Eulerian coordinatesystem ρ is the density v is the particle velocity e is theinternal energy of unit mass σij is the Cauchy stress tensorfi is the body force qi is the heat flux and subscripts i and j

stand for the direction of coordinateAt the same time meshes of explosive and the air were

joined with common nodes and so as to rock and protectingpipe en the fluid-solid coupling was defined between themeshes of the explosive air rock and protecting pipe by thekeyword In addition according to the characteristics ofblasting process the time step of the simulation is 067 andthe computation time is 0004 s

34 Simulation Results Analysis e Postprocessing soft-ware LS-PREPOST was used to draw the diagrams of theevolution law of explosion stress wave and crack propaga-tion of different simulation cases as shown in Figures 9ndash11

In general for regular blasthole blasting the explosionstress uniformly acts on the wall of blasthole and the shapeof blast stress wave is round and then the blast-inducedcrack forms and expands under the blast loading Due to thecharacters of blast loading the gas pressure acting onblasthole wall in all directions can be considered as equiv-alent so the well-distributed blast-induced cracks generatenear the blasthole which is consistent with the classicalblasting theory

Shock and Vibration 7

However by comparing 1 simulation case the blast-induced crack propagation law and the transmission law ofexplosion stress wave of 2 simulation case and 3 simu-lation case were greatly changed under the effect of water jetslot and blasthole wall protection materials On one handblasting energy focus forms at the initial stage of the ex-plosion which promotes the initial microcrack produced atthe direction of water jet slot And nothing but air is in thewater jet slot which caused the formation of low-pressurezone so detonation products have priority to flow along thedirection of water jet slot en the high-pressure and high-velocity gas products wedge into the slot further leading tocrack initiation and extension along the desired direction asshown in Figures 10 and 11 On the other hand as the failureof blasthole wall protectionmaterial makes a large amount ofconsumption of blast energy the formation of microcrack ofthe remaining rock mass was restrained Furthermorethe blasthole wall protection material is in a molten stateduring the blasting which will wedge into the unexpected

microcracks and then the ldquogas edge effectrdquo of gas productwill be greatly weakened So the dual purpose of directionalblast-induced crack propagation and remaining rock massprotection is realized

To further understand the transmission law of blaststress wave and the change regularity of blasting strain underdifferent conditions monitoring points were set in thenumerical simulation model and its schematic diagram isshown in Figure 12 where Dm stands for the distance be-tween the monitoring point and the center of blasthole rbstands for the radius of blasthole and αn is the angle betweentwo lines one is the connection between blasthole center andwater jet slot and the another is the connection betweenblasthole center and monitoring point

Figures 13ndash15 show the P-T curves of different simu-lation cases from which we can see that with the increase ofDm the pressure of different cases almost shows a trend ofgradual decrease but the pressure of different monitoringpoints of different cases shows a different changing trendFor 1 simulation case when Dmrb is certain each P-Tcurve shows the same trend because of the explosion at isbecause the explosion stress uniformly acts on the wall ofblasthole during blasting which is consistent with experi-ment test result For 2 simulation case when αn is 0deg the

Table 3 Parameters of rock

Density (gcm3) Elastic modulus (MPa) Tangent modulus (MPa) Poisson ratio Yield strength (MPa) SRC SRP Failure strain250 225times104 420times103 022 300 0 0 006

Table 4 Parameters of blasthole wall protection material

Density (gcm3) Elastic modulus (MPa) Poisson ratio Yield strength (MPa) SRC SRP Failure strain143 300times103 03 18times10minus1 0 0 01

Table 5 Parameters of explosive and its EOS equation

ρe (gcm3) vD (cmμs) Pcut (MPa) A (MPa) B (MPa) R1 R2 ω

170 083 295times104 855times105 205times104 460 135 025

Table 6 Parameters of air and its EOS equation

ρa (gcm3) C0 C1 C2 C3 C4 C5 C6

120times10minus3 000 000 000 000 040 040 000

Nonreflected boundaryRock

Nonreflected boundary

A

75

150

150

75

Blasthole wall protection material

Explosive

Water jet slot

(a) (b)

Figure 8 Numerical simulation model (a) 3 simulation model (b) enlargement of part A

8 Shock and Vibration

peak value of the measuring point is smaller than that ofregular blasting but the valley value is bigger than that ofregular blasthole blasting at is to say the rock will besubjected to tensile stress As we know the tensile strength ofrock is far less than its compressive strength so the rock isvulnerable to failure [34] which suggest that the existence ofthe water jet slot changed the distribution laws of stress fieldsduring blasting let the blast-induced crack initiation andpropagation in the direction of water jet slot

For 3 simulation case when αn is 0deg though the peakvalue continues to decline valley value is 4040 greaterthan that of 2 simulation case Moreover the action time of

tensile stress of 3 simulation case is much longer than thatof 2 simulation case When αn is 90deg the peak value is2534 and 2966 smaller than that of 2 simulation caseand 1 simulation case respectively which demonstratesthat the existence of blasthole wall protection material hascreated more favorable conditions for the blast-inducedcrack propagation along the direction of water jet slotand the protection of blasthole wall during blasting which isconsistent with the above analysis

Figures 16ndash18 present the effective stress curves of dif-ferent simulation cases For 1 simulation case as the ex-plosion stress uniformly acts on the wall of blasthole during

Blast stress wave Blast-induced crack

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 9 Diagram of blast-induced crack propagation and stress wave transmission of 1 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focus Blast-induced crack

Stress concentration

Blast stress wave

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 10 Diagram of blast-induced crack propagation and stress wave transmission of 2 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focusBlast-induced crack

Stress concentration

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 11 Diagram of blast-induced crack propagation and stress wave transmission of 3 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Shock and Vibration 9

αn

N2-4

N2-3

N2-2

N2-1

N1-110 10 1020

N1-2 N1-3 N1-4

90deg

Dm

rb

Figure 12 Schematic diagram of monitoring point layout

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 13 P-T curve of different monitoring points of 1 simulation case (a) αn 0deg (b) αn 90deg

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

(b)

Figure 14 P-T curve of different monitoring points of 2 simulation case (a) αn 0deg (b) αn 90deg

10 Shock and Vibration

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 15 P-T curve of different monitoring points of 3 simulation case (a) αn 0deg (b) αn 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(b)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(c)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(d)

Figure 16 Effective stress curve of different monitoring points of 1 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 11

blasting the effective stress of each curve shows the sametrend if Dmrb is certain and the effective stress decreasesgradually and becomes stable with the increase of Dmrb For2 simulation case the peak value of effective stress de-creases with the increase of Dmrb and αn at is to say ifDmrb is certain the rock located at different directionsaround the blasthole suffered different effective stress thecloser the rock gets to the direction of water jet the biggerthe effective stress the rock suffered For 3 simulation casethe variation trend of effective stress is similar to that of 2simulation case but the peak value of each effective stresscurve is quite different By comparing each effective stresscurve of 2 simulation case and 3 simulation case we cansee that in the direction of water jet slot the peak value ofeffective stress of 3 simulation case is always bigger thanthat of 2 simulation case However in the direction per-pendicular to the direction of the jet slot the peak value ofeffective stress of 3 simulation case is always smaller than

that of 2 simulation case which indicates that the existenceof blasthole wall protection material is not only very ben-eficial to the ldquoguiding effectrdquo of blast-induced crack prop-agation by water jet slot but also beneficial to reduce blast-induced damage of remaining rock mass

Moreover by comparing Figures 16(d) 17(d) and 18(d)we can see that in the direction of water jet slot the effectivestress of 2 simulation case decreases gradually and whenDmrb is 20 the distribution-evolution law of effective stressis similar to that of 1 simulation case However for 3simulation case when Dmrb is 20 the peak value of effectivestress is bigger than that of 2 simulation case and thegrowing trend of effective stress shows a large fluctuationwhich suggested that the rock suffered the ldquoguiding effectrdquo bywater jet slot In addition in the other direction of blastholethe distribution-evolution law of effective stress is similar tothat of 1 simulation case at is to say the bigger Dmrb isthe weaker the ldquoguiding effectrdquo and ldquoblasthole wall

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 17 Effective stress curve of different monitoring points of 2 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

12 Shock and Vibration

protection effectrdquo by water jet slot and wall protectionmaterial are

4 Conclusions

In summary some conclusions can be summarized asfollows

e experiment test on dynamic blast strain was con-ducted and the results indicated that under the combinedeffect of blasthole wall protection material and water jet slotthe blasting strain fields were changed by comparing withthe regular blasthole blasting In the direction of water jetslot the PSPV was increased by 8500 and in the directionperpendicular to the direction of water jet slot the PSPV wasreduced by 7021

Numerical simulation results suggest that the existence ofwater jet slot and blasthole wall protection material can affectthe distribution and evolution law of explosive stress waveand let the stress concentration occur at the tip of water jet

slot which promotes blast-induced crack propagation alongthe specific direction and minimizes the blast-induceddamage of remaining rock mass Moreover the bigger Dmrb is the weaker the ldquoguiding effectrdquo and ldquoblasthole wallprotection effectrdquo by water jet slot and wall protection ma-terial are

Both the experiment test result and the numericalsimulation results indicated that the existence of blastholewall protection material is not only beneficial to the ldquoguidingeffectrdquo of blast-induced crack propagation of water jet slotbut also beneficial to reduce blast-induced damage ofremaining rock mass

Future research work will be focused on the applicationsin practical engineering of this approach

Data Availability

Readers can access the data supporting the conclusions ofthe study by sending a mail to the corresponding author

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 18 Effective stress curve of different monitoring points of 3 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 13

(e-mail dengfengcqu163com) and all data can be cosh-ared without restriction

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

Financial support for this work was provided by the NaturalScience Foundation of Southwest University of Science andTechnology (18zx7124) In particular the authors thank ME D Y Li and M E F W Yan for their kind help inexperimental investigation and sincere suggestion

References

[1] Z N Zhao X T Feng Y X Xiao et al ldquoMicroseismiccharacteristics and rockburst risk of deep tunnel constructedby different excavation methodsrdquo Chinese Journal of Geo-technical Engineering vol 38 no 5 pp 0867ndash0876 2016

[2] Z C Zhang ldquoControl in blasting engineeringrdquo ChineseJournal of Underground Space and Engineering vol 9 no 5pp 1208ndash1214 2013

[3] Y Wang ldquoStudy of the dynamic fracture effect using slottedcartridge decoupling charge blastingrdquo International Journal ofRock Mechanics and Mining Sciences vol 96 pp 34ndash46 2017

[4] S S Rathore and S Bhandari ldquoControlled fracture growth byblasting while protecting damages to remaining rockrdquo RockMechanics and Rock Engineering vol 40 no 3 pp 317ndash3262007

[5] S H Cho Y Nakamura B Mohanty H S Yang andK Kaneko ldquoNumerical study of fracture plane control inlaboratory-scale blastingrdquo Engineering Fracture Mechanicsvol 75 no 13 pp 3966ndash3984 2008

[6] R S Yang Y B Wang and L Y Yang ldquoDynamic causticexperimental study of crack propagation in two borehole cutblastingrdquo Journal of China University of Mining amp Technologyvol 41 no 6 pp 868ndash872 2012

[7] WM Liang X L Yang and Y Q Yu ldquoResearch on theory ondirectional fracture controlled blastingrdquo Journal of LiaoningTechnical University vol 25 no 5 pp 702ndash704 2006

[8] J S Song Y B Wang X T Gao et al ldquoe mechanism ofdirectional fracture controlled blasting and its applicationrdquoJournal of Mining Science and Technology vol 1 no 1pp 16ndash28 2016

[9] Y Wang ldquoExperimental research on the influence of anempty-hole defect on crack connections between a direc-tionally fractured blast holerdquo Journal of Testing and Evalu-ation vol 45 no 6 pp 2139ndash2150 2017

[10] Z Li W Chen and H Hao ldquoNumerical study of sandwichpanel with a new bi-directional load-self-cancelling (LSC)core under blast loadingrdquo =in-Walled Structures vol 127pp 90ndash101 2018

[11] K Katsuyama H Kiyokawa and K Sassa ldquoControl thegrowth of cracks from a borehole by a new method of smoothblastingrdquo Mining Safety vol 29 pp 16ndash23 1983

[12] W L Fourney D B Barker and D C Holloway ldquoModelstudies of explosive well stimulation techniquesrdquo In-ternational Journal of Rock Mechanics and Mining Sciences ampGeomechanics Abstracts vol 18 no 2 pp 113ndash127 1981

[13] W L Fourney D B Barker and D C Holloway ldquoModelstudies of well stimulation using propellant chargesrdquo

International Journal of Rock Mechanics and Mining Sciencesamp Geomechanics Abstracts vol 20 no 2 pp 91ndash101 1983

[14] B Mohanty ldquoExplosive generated fractures in rock and rocklike materialsrdquo Engineering Fracture Mechanics vol 35 no 4-5 pp 889ndash898 1990

[15] B Mohanty ldquoFracture-plane control blasts with satelliteholesrdquo in Proceedings of 3rd International Symposium on RockFragmentation by Blasting pp 407ndash418 Australasian Instituteof Mining and Metallurgy Parkville Australia August 1990

[16] Y G Du Z C Zhang and T L Li ldquoStudies on mechanicaleffect produced by the V-shaped notch borehole blastingrdquoExplosion and Shock Waves vol 11 pp 26ndash30 1991

[17] Q Zong ldquoeoretical study on the cracking mechanism ofnotched borehole blastingrdquo Coal Mine Blasting vol 1pp 12ndash16 1995

[18] Q Zong ldquoInvestigations into mechanism of crack formationfor grooved hole-well blastingrdquo Chinese Journal of Geo-technical Engineering vol 20 no 1 pp 30ndash33 1998

[19] S H Cho Y Nakamura and K Kaneko ldquoDynamic fractureprocess analysis of rock subjected to a stress wave and gaspressurizationrdquo International Journal of Rock Mechanics andMining Sciences vol 41 no 3 pp 433ndash440 2004

[20] Y Zhang ldquoDynamic numerical simulation for the mechanismof V-shaped notch blastingrdquo Explosive Materials vol 38no 4 pp 1ndash5 2009

[21] R S Yang and Y B Wang ldquoDynamic caustic experiment onfracture behaviors of flawed material induced by pre-notchedblastingrdquo Explosive and Shock Waves vol 36 no 2pp 145ndash152 2016

[22] R S Yang C X Ding L Y Yang P Xu and C Chen ldquoHoledefects affect the dynamic fracture behavior of nearby runningcracksrdquo Shock and Vibration vol 2018 Article ID 58943568 pages 2018

[23] Z W Yue Y Guo X Wang et al ldquoInfluence of empty holeshape on directional fracture controlled blasting of rockrdquoRock and Soil Mechanics vol 37 no 2 pp 376ndash382 2016

[24] Z Yue P Qiu R Yang S Zhang K Yuan and Z Li ldquoStressanalysis of the interaction of a running crack and blastingwaves by caustics methodrdquo Engineering Fracture Mechanicsvol 184 pp 339ndash351 2017

[25] B Chen C Liu and J X Yang ldquoAnalysis and application oncontrolling thick hard roof caving with deep-hole positionpresplitting blastingrdquoAdvances in Civil Engineering vol 2018Article ID 9763137 15 pages 2018

[26] Y H Zhu and X P Xu ldquoDamage control characteristics fornotched blasting based on the damage mechanismrdquo Journal ofChina Coal Society vol 42 no 2 pp 369ndash376 2017

[27] X H Li L Yang J S Wang et al ldquoe natural frequencycharacteristic of the self-excited oscillation pulsed water jetdevicerdquo Journal of China Coal Society vol 25 no 6pp 641ndash644 2000

[28] X H Li Y Y Lu Y Zhao et al ldquoStudy on improving thepermeability of soft coal seam with high pressure pulsed waterjetrdquo Journal of China Coal Society vol 33 no 12 pp 1386ndash1390 2007

[29] Y Kang X C Wang X F Yang et al ldquoNumerical simulationof control blasting with borehole protecting and water jetslotting in soft rock massrdquo Disaster Advances vol 5 no 4pp 933ndash938 2012

[30] J-G Kim and J-J Song ldquoAbrasive water jet cutting methodsfor reducing blast-induced ground vibration in tunnel ex-cavationrdquo International Journal of Rock Mechanics andMining Sciences vol 75 pp 147ndash158 2015

14 Shock and Vibration

[31] Y Kang D D Zheng D F Su et al ldquoModel of directionalshaped blasting assisted with water jet and its numericalsimulationrdquo Journal of Vibration and Shock vol 34pp 182ndash188 2015

[32] D Su Y Kang F Yan D Zheng X Wang and M WeildquoCrack propagation law affected by natural fracture and waterjet slot under blast loadingrdquo Combustion Explosion andShock Waves vol 54 no 6 pp 747ndash756 2018

[33] Y B Wang ldquoRock dynamic fracture characteristics based onNSCB impact methodrdquo Shock and Vibration vol 2018 Ar-ticle ID 3105384 13 pages 2018

[34] J Dai Dynamic Behaviors and Blasting =eory of RockMetallurgical Industry Press Beijing China 2013

[35] LSTC LS-DYNAKeyword Userrsquos Manual Livermore SoftwareTechnology Corporation Livermore CA USA 2007

Shock and Vibration 15

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Page 2: ExperimentalStudyandNumericalSimulationofDynamic Stress ...downloads.hindawi.com/journals/sv/2019/1659175.pdf,kLL jLL xLL L xLL jLL,kLL L L©L, L©Lk L©Lff L©Lx _NF ig E NFE #_#YNIkff©,Ifiig

fracture and fragmentation mechanism due solely to thestress wave in blasting Zhang [20] simulated the stressdistribution law by ANSYSLS-DYNA and the dynamicseam forming mechanism is also analyzed based on thefracture mechanics theory Yang et al [21 22] studied thecrack propagation and changes in stress intensity at thecrack tips of the two V-notched borehole by the blastloading system using dynamic reflected caustics e ex-perimental results show that the crack tips do not meetdirectly but are deflected and become anisotropic and thecrack propagation velocity first decreases oscillates andthen gradually increases to peak followed by a decreaseuntil the oscillations stop Yue et al [23 24] conductedmodel experiments to investigate the influence of emptyholes with different shapes on directional fracture-controlled blasting of rock by using new digital laser dy-namic caustics e results show that the preset rhombichole can achieve fine directional fracture-controlledblasting and effectively ensure the forming effect ofblasting around the roadway Chen et al [25] analyzed themechanism of rock fracturing between holes in deep-holepresplit blasting and the crack evolution under the syn-ergistic action of dynamic and static loads and the scope ofstress-induced cracks around blastholes and the maximumlength of secondary cracks induced by detonation gas werecalculated Zhu and Xu [26] compared the stress anddamage distribution of conventional circle hole and notchhole by implementing a user-defined statistical damagemodel based on the secondary development of the LS-DYNA and the results demonstrate that two mechanicaleffects are induced by the notch and high stress concen-tration is generated at the edge of the notch and the stress atthe other part of blasthole is reduced

Above research studies concentrate mainly on theV-notch directional blasting technology with mechanicalgrooving tool assistance and demonstrate that this method issuperior to the traditional blasting technology to control thedirection of blast-induced crack propagation However thismethod has a disadvantage of notching tool to be stuck andwear and tear especially for the soft surrounding rockblasting In order to solve this problem the unique characterfor low damage directional control cutting and highlyenergy accumulation of water jet attracted the attention ofresearchers (Figure 1) [27 28] and then the directional-controlled blasting with water jet assistance was put forward[29ndash32] Its mechanism was analyzed and the blast-inducedcrack initiation criterion along the direction of the water jetslot under blast loading was established Furthermore theeffect of water jet slot for reducing blast-induced groundvibration in tunnel excavation was analyzed by Kim andSong [30] and the nonlinear hydrokinetics code (AUTO-DYNA) was used to simulate the effect of reduction of blast-induced vibrations by abrasive water jet cutting

Based on above studies an attempt was made in thispaper to study the dynamic evolution law of blasting strainunder different conditions An experiment was performed toinvestigate the evolution law of dynamic strain of differentmodels en numerical simulation for the transmissionand reflection of blast stress wave and the propagation law of

blast-induced crack were performed by using the FEMsoftware ANSYSLS-DYNA

2 Experimental Test on DynamicBlasting Strain

21 Test Instrument and Test Principle Blast stress wave hasthe characteristics of wide band high upper limit frequencyand large amplitude change so the test instrument musthave a high sampling frequency In this paper a multi-channel dynamic analysis signal testing system produced byDonghua Testing Technology Co Ltd was applied itcomprises an ultrahigh dynamic strain meter with eightchannels a blast loading system and a computer used tocollect blasting data the connection of the test system isshown in Figure 2 and the procedure of experimental test isshown in Figure 3

PMMA was used in these blast tests in that it almostshares similar fracture behaviors with brittle rock underdynamic conditions [33] PMMA specimens were 300mmtimes 300 mmtimes 2 mm in size and its parameters are shownin Table 1 A blasthole was placed in the center of thespecimen with the center of the blasthole 150mm from thefour sides All the blastholes are 3mm in radius

In order to investigate dynamic strain law underdifferent blasting conditions three shapes of blastholeswere designed 1 test model has one regular blasthole 2test model has one blasthole with two water jet slot alongthe horizontal axis and 3 test model has one water jetslotted blasthole with the blasthole wall protection ma-terial mounted on the two opposite surfaces of theblasthole PVC material was used as the wall-protectedmaterial Each test model and its strain gauge arrange-ment are shown in Figure 4 In addition each blastholewas charged by 40mg explosive which was made ofpropellant and the spark starter was used as a detonatingdevice

22 Experimental Results Analysis Table 2 and Figures 5ndash7present different types of strain values under three differentblasting models respectively For 1 test model mean strainpeak value (PSPV) at E1-1 test point is very close to thePSPV at E1-3 test point and the mean strain peak value atfour test points is close to the same In addition the strainwave evolution law of E1-1 test point is almost the same asthat of E1-3 test point and so as to E1-2 test point and

Water jet slot

Pump pressure 20MPa

Figure 1 Coal and rock mass cutting using water-only jet

2 Shock and Vibration

E1-4 test point which shows that when the explosive ex-plodes in a regular blasthole the blasting load almost evenlyworks on the circular blasthole surface [34]

By comparing Figure 5 with Figure 6 we can see that thePSPV value at E2-1 test point is 3667 greater than PSPVat E1-1 test point and the PSPV at E2-2 test point is 179greater than the PSPV at E1-2 test pointat is because thewater jet slot results in stress concentrations along the di-rection of the water jet slot while detonation gases work on

the blasthole surface or stress waves arrive at the tip of thewater jet slot during blasting In addition the positive strainpeak value (PSPV) and mean strain peak value (MSPV) atE1-3 test point and E1-4 test point are almost the same asthe PSPV and MSPV at E2-3 test point and E2-4 testpoint and so as to the evolution law of explosive strainwave It can be seen from the above analysis that the waterjet slot changed the law of stress field distribution duringthe blasting which results in the stress concentrations

Experimental testspecimens

Strain-compensated

Ultra dynamic strainmeasuring systemSignal sensor Data processing

system

Front view

Back view

Figure 2 Diagram of test system connection

If the installation of signal sensor is

properNo

Yes

Installingthe experimental

test specimens

Charging and connecting the

test circuit

Starting the ultra dynamic strain

measuring system

If the connection of test circuit is

proper

Detonating explosive

No

Yes

Test data processing and

analysis

Replace the signal sensor

Replace the test circuit

Figure 3 Diagram of experimental test procedure

Table 1 Parameters of PMMA

Density (gcm3) Poisson ratio Elastic modulus (GPa) Longitudinal wave velocity (cmμs) Shear wave speed (cmμs)12 031 61 23times105 126times107

Shock and Vibration 3

along the direction of the water jet slot However in thedirection perpendicular to water jet slot the existence ofwater jet slot has hardly changed the distribution of stressfield

For 3 test model the existence of blasthole protectionmaterial has greatly changed the distribution law and evo-lution law of the explosive strain wave On one hand thePSPV in the direction of the water jet slot gradually in-creases the PSPV at E2-1 test point is 3667 greater thanthe PSPV at E1-1 test point the PSPV at E3-1 test point is3537 greater than PSPV at E2-1 test point and the PSPVat E3-1 test point is 8500 greater than the PSPV at E1-1test point On the other hand the blasting strain values in thedirection perpendicular to water jet slot respectively de-crease to smaller values Just in regard to the PSPV the figure(623167 με) at E2-3 test point sees a 437 decrease endingup with 350768 με at E3-3 test point and the figures at E2-4 test point and E3-4 test point almost share the samedecreasing proportion It is suggested that in contrast withdirectional-controlled blasting with water jet assistance theexistence of blasthole wall protection material can sharplyreduce the energy of stress wave working on the remainingsides so as to achieve the purpose of protecting the sur-rounding rock

Furthermore by comparing the blasting strain of 2 testmodel and 3 test model we can see that in the direction ofwater jet slot the blast strain is much greater than that in the

direction perpendicular to water jet slot For 2 test modelthe PSPV at E2-1 test point sees a 2836 decrease from869829 με reaching 623167 με at E2-3 test point Besidesfor 3 test model compared with PSPV (1177456 με) at E3-1 test point the PSPV at E3-3 test point falls by 7021ending at 350768 με Both the two decreasing trendsdemonstrate that water jet slot can have an obvious effect onstress concentration along the direction of water jet slot so asto more easily generate perforative fractures along this di-rection during blasting and the remaining rock can be betterprotected

To sum up some conclusions can be summarized fromthe experimental test as follows

(1) Under the combined effect of blasthole wall pro-tection material and water jet slot the PSPV bycomparing with regular blasthole blasting was in-creased by 8500 in the direction of water jet slotand the PSPV in the direction perpendicular to thedirection of water jet slot was reduced by 7021

(2) In contrast with directional-controlled blasting withwater jet assistance the existence of blasthole wallprotection material is not only beneficial to theldquoguiding effectrdquo of blast-induced crack propagationof water jet slot but also beneficial to reduce blast-induced damage of remaining rock mass

Regular blasthole

2

E1-4

E1-3

E1-1 E1-24

(a)

Water jet slotted blasthole

2

E2-1 E2-24

E2-4

E2-3

(b)

Water jet slotted blastholewith wall protection material

E3-4

E3-3

2

E3-1 E3-2

4

(c)

Figure 4 Sketches of three different blasting models and the strain gauge arrangement (a) 1 test model (b) 2 test model and (c) 3 testmodel

Table 2 Strain values for three different blasting models

Test model Strain valueValues (με)

Channel 1 Channel 2 Channel 3 Channel 4

Model 1Positive strain peak value 636454 537698 672342 570690Negative strain peak value minus495945 minus248893 minus722151 minus396569Mean strain peak value 83223 73074 92998 78041

Model 2Positive strain peak value 869829 633962 623167 520278Negative strain peak value minus341492 minus280124 minus718531 minus388996Mean strain peak value 171153 132421 80121 63676

Model 3Positive strain peak value 1177456 810468 350768 295034Negative strain peak value minus772859 minus348843 minus368530 minus271644Mean strain peak value 224876 189897 27480 12654

4 Shock and Vibration

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 636454μεNSPV ndash495945μεMSPV 83223με

(a)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 537698μεNSPV ndash248893μεMSPV 73074με

(b)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 672342μεNSPV ndash722151μεMSPV 92998με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 570690μεNSPV ndash396569μεMSPV 78041με

(d)

Figure 5 Waveform curve of dynamic strain for 1 test model (a) E1-1 test point (b) E1-2 test point (c) E1-3 test point and (d) E1-4test point

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 869829μεNSPV ndash341492μεMSPV 171153με

(a)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 633962μεNSPV ndash280124μεMSPV 132421με

(b)

Figure 6 Continued

Shock and Vibration 5

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 623167μεNSPV ndash718531μεMSPV 80121με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 520278μεNSPV ndash388996μεMSPV 63676με

(d)

Figure 6 Waveform curve of dynamic strain for 2 test model (a) E2-1 test point (b) E2-2 test point (c) E2-3 test point and (d) E2-4test point

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 1177456μεNSPV ndash772859μεMSPV 224876με

(a)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 810468μεNSPV ndash348843μεMSPV 189897με

(b)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 350768μεNSPV ndash368530μεMSPV 27480με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 295034μεNSPV ndash271644μεMSPV 12654με

(d)

Figure 7 Waveform curve of dynamic strain for 3 test model (a) E3-1 test point (b) E3-2 test point (c) E3-3 test point and (d) E3-4test point

6 Shock and Vibration

3 Numerical Simulation of BlastStress Evolution

e FEM software ANSYSLS-DYNA and the post-processing software LS-PREPOST were applied to in-vestigate the blasting stress wave evolution law and the blast-induced crack propagation law for different conditions

31 Numerical Simulation Model ree simulation caseswere conducted by ANSYSLS-DYNA Due to the symmetryof the simulated object both simulation cases applied aquasi-2D simulation model For each case the size of rock is150 cmtimes 150 cmtimes 03 cm the diameter of blasthole is 5 cmthe thickness of the blasthole wall protection material is05 cm and the size of the water jet slot is25 cmtimes 05 cmtimes 03 cm e 3 simulation model is shownin Figure 8

32 Material Model

321 Rock Material type 3 of LS-DYNA (lowastMAT_PLASTIC_KINEMATIC) was applied to model the rock [35] and itsparameters are shown in Table 3

322 BlastholeWall ProtectionMaterial Material type 3 ofLS-DYNA (lowastMAT_PLASTIC_KINEMATIC) was applied tomodel the blasthole wall protection material [35] and itsparameters are shown in Table 4

323 Explosive Material type 8 of LS-DYNA(lowastMAT_HIGH_EXPLOSIVE_BURN) was chosen as theexplosive model and the pressure released by the chemicalenergy in the engineering calculations was modelled by theJonesndashWilkinsndashLee equation of state e JWL EOS can bewritten in the following form [35]

Pe A 1minusω

R1V1113888 1113889e

minusR1V+ B 1minus

ωR2V

1113888 1113889eminusR2V

+ωEe

V (1)

where Pe is the pressure produced by the detonationproducts from explosive where ω A B R1 and R2 are user-defined input parameters V is the relative volume and Ee isthe internal energy per initial volume as shown in Table 5

324 Air Air was modelled by the material type 9 of LS-DYNA (lowastMAT_NULL) with the Gruneisen equation epressure Pa can be calculated by [35]

Pa C0 + C1μ + C2μ2 + C3μ3 + C4 + C5μ + C6μ2( 1113857Ea

μ 1

Vaminus 1

⎧⎪⎪⎪⎪⎨

⎪⎪⎪⎪⎩

(2)

where C0 C1 C2 C3 C4 C5 and C6 are user-definedconstants ρa is the density of air Va is the relative

volume of air Ea is the internal energy of air as shown inTable 6

33 Numerical Calculation Algorithm Lagrange algorithmhas the priority of less computation time and accuratelydescribing the boundary movement of structure so it isalways used to analyze the explosive detonation Howeverit has a big disadvantage of causing element distortion andeven leads to the termination of calculation when dealingwith the large deformation numerical calculation Inorder to avoid the above problem fluid-solid couplingalgorithm was adopted for the analysis of the explosivedetonation of which ALE algorithm was used for ex-plosive and air and Lagrange algorithm for rock andprotecting pipe e material derivative equation and thegoverning equations of the ALE algorithm can beexpressed as follows [35]

df(X t)

dt

zf(ξ t)

zt+ vi minuswi( 1113857

zf(x t)

zxi

zρzt

ρzυi

zx+ ωi

zρzx

ρzυi

zt+ ρωi

zυi

zxj

zσij

zxj

+ ρfi

ρze

zt σij

zυi

zxj

minuszq

zxj

minus ρωi

ze

zxi

(3)

where f is the physical quantity vi is the velocity of particleX ωi is the velocity of the computational grid xi is theLagrangian coordinate system yi is the Eulerian coordinatesystem ρ is the density v is the particle velocity e is theinternal energy of unit mass σij is the Cauchy stress tensorfi is the body force qi is the heat flux and subscripts i and j

stand for the direction of coordinateAt the same time meshes of explosive and the air were

joined with common nodes and so as to rock and protectingpipe en the fluid-solid coupling was defined between themeshes of the explosive air rock and protecting pipe by thekeyword In addition according to the characteristics ofblasting process the time step of the simulation is 067 andthe computation time is 0004 s

34 Simulation Results Analysis e Postprocessing soft-ware LS-PREPOST was used to draw the diagrams of theevolution law of explosion stress wave and crack propaga-tion of different simulation cases as shown in Figures 9ndash11

In general for regular blasthole blasting the explosionstress uniformly acts on the wall of blasthole and the shapeof blast stress wave is round and then the blast-inducedcrack forms and expands under the blast loading Due to thecharacters of blast loading the gas pressure acting onblasthole wall in all directions can be considered as equiv-alent so the well-distributed blast-induced cracks generatenear the blasthole which is consistent with the classicalblasting theory

Shock and Vibration 7

However by comparing 1 simulation case the blast-induced crack propagation law and the transmission law ofexplosion stress wave of 2 simulation case and 3 simu-lation case were greatly changed under the effect of water jetslot and blasthole wall protection materials On one handblasting energy focus forms at the initial stage of the ex-plosion which promotes the initial microcrack produced atthe direction of water jet slot And nothing but air is in thewater jet slot which caused the formation of low-pressurezone so detonation products have priority to flow along thedirection of water jet slot en the high-pressure and high-velocity gas products wedge into the slot further leading tocrack initiation and extension along the desired direction asshown in Figures 10 and 11 On the other hand as the failureof blasthole wall protectionmaterial makes a large amount ofconsumption of blast energy the formation of microcrack ofthe remaining rock mass was restrained Furthermorethe blasthole wall protection material is in a molten stateduring the blasting which will wedge into the unexpected

microcracks and then the ldquogas edge effectrdquo of gas productwill be greatly weakened So the dual purpose of directionalblast-induced crack propagation and remaining rock massprotection is realized

To further understand the transmission law of blaststress wave and the change regularity of blasting strain underdifferent conditions monitoring points were set in thenumerical simulation model and its schematic diagram isshown in Figure 12 where Dm stands for the distance be-tween the monitoring point and the center of blasthole rbstands for the radius of blasthole and αn is the angle betweentwo lines one is the connection between blasthole center andwater jet slot and the another is the connection betweenblasthole center and monitoring point

Figures 13ndash15 show the P-T curves of different simu-lation cases from which we can see that with the increase ofDm the pressure of different cases almost shows a trend ofgradual decrease but the pressure of different monitoringpoints of different cases shows a different changing trendFor 1 simulation case when Dmrb is certain each P-Tcurve shows the same trend because of the explosion at isbecause the explosion stress uniformly acts on the wall ofblasthole during blasting which is consistent with experi-ment test result For 2 simulation case when αn is 0deg the

Table 3 Parameters of rock

Density (gcm3) Elastic modulus (MPa) Tangent modulus (MPa) Poisson ratio Yield strength (MPa) SRC SRP Failure strain250 225times104 420times103 022 300 0 0 006

Table 4 Parameters of blasthole wall protection material

Density (gcm3) Elastic modulus (MPa) Poisson ratio Yield strength (MPa) SRC SRP Failure strain143 300times103 03 18times10minus1 0 0 01

Table 5 Parameters of explosive and its EOS equation

ρe (gcm3) vD (cmμs) Pcut (MPa) A (MPa) B (MPa) R1 R2 ω

170 083 295times104 855times105 205times104 460 135 025

Table 6 Parameters of air and its EOS equation

ρa (gcm3) C0 C1 C2 C3 C4 C5 C6

120times10minus3 000 000 000 000 040 040 000

Nonreflected boundaryRock

Nonreflected boundary

A

75

150

150

75

Blasthole wall protection material

Explosive

Water jet slot

(a) (b)

Figure 8 Numerical simulation model (a) 3 simulation model (b) enlargement of part A

8 Shock and Vibration

peak value of the measuring point is smaller than that ofregular blasting but the valley value is bigger than that ofregular blasthole blasting at is to say the rock will besubjected to tensile stress As we know the tensile strength ofrock is far less than its compressive strength so the rock isvulnerable to failure [34] which suggest that the existence ofthe water jet slot changed the distribution laws of stress fieldsduring blasting let the blast-induced crack initiation andpropagation in the direction of water jet slot

For 3 simulation case when αn is 0deg though the peakvalue continues to decline valley value is 4040 greaterthan that of 2 simulation case Moreover the action time of

tensile stress of 3 simulation case is much longer than thatof 2 simulation case When αn is 90deg the peak value is2534 and 2966 smaller than that of 2 simulation caseand 1 simulation case respectively which demonstratesthat the existence of blasthole wall protection material hascreated more favorable conditions for the blast-inducedcrack propagation along the direction of water jet slotand the protection of blasthole wall during blasting which isconsistent with the above analysis

Figures 16ndash18 present the effective stress curves of dif-ferent simulation cases For 1 simulation case as the ex-plosion stress uniformly acts on the wall of blasthole during

Blast stress wave Blast-induced crack

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 9 Diagram of blast-induced crack propagation and stress wave transmission of 1 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focus Blast-induced crack

Stress concentration

Blast stress wave

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 10 Diagram of blast-induced crack propagation and stress wave transmission of 2 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focusBlast-induced crack

Stress concentration

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 11 Diagram of blast-induced crack propagation and stress wave transmission of 3 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Shock and Vibration 9

αn

N2-4

N2-3

N2-2

N2-1

N1-110 10 1020

N1-2 N1-3 N1-4

90deg

Dm

rb

Figure 12 Schematic diagram of monitoring point layout

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 13 P-T curve of different monitoring points of 1 simulation case (a) αn 0deg (b) αn 90deg

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

(b)

Figure 14 P-T curve of different monitoring points of 2 simulation case (a) αn 0deg (b) αn 90deg

10 Shock and Vibration

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 15 P-T curve of different monitoring points of 3 simulation case (a) αn 0deg (b) αn 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(b)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(c)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(d)

Figure 16 Effective stress curve of different monitoring points of 1 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 11

blasting the effective stress of each curve shows the sametrend if Dmrb is certain and the effective stress decreasesgradually and becomes stable with the increase of Dmrb For2 simulation case the peak value of effective stress de-creases with the increase of Dmrb and αn at is to say ifDmrb is certain the rock located at different directionsaround the blasthole suffered different effective stress thecloser the rock gets to the direction of water jet the biggerthe effective stress the rock suffered For 3 simulation casethe variation trend of effective stress is similar to that of 2simulation case but the peak value of each effective stresscurve is quite different By comparing each effective stresscurve of 2 simulation case and 3 simulation case we cansee that in the direction of water jet slot the peak value ofeffective stress of 3 simulation case is always bigger thanthat of 2 simulation case However in the direction per-pendicular to the direction of the jet slot the peak value ofeffective stress of 3 simulation case is always smaller than

that of 2 simulation case which indicates that the existenceof blasthole wall protection material is not only very ben-eficial to the ldquoguiding effectrdquo of blast-induced crack prop-agation by water jet slot but also beneficial to reduce blast-induced damage of remaining rock mass

Moreover by comparing Figures 16(d) 17(d) and 18(d)we can see that in the direction of water jet slot the effectivestress of 2 simulation case decreases gradually and whenDmrb is 20 the distribution-evolution law of effective stressis similar to that of 1 simulation case However for 3simulation case when Dmrb is 20 the peak value of effectivestress is bigger than that of 2 simulation case and thegrowing trend of effective stress shows a large fluctuationwhich suggested that the rock suffered the ldquoguiding effectrdquo bywater jet slot In addition in the other direction of blastholethe distribution-evolution law of effective stress is similar tothat of 1 simulation case at is to say the bigger Dmrb isthe weaker the ldquoguiding effectrdquo and ldquoblasthole wall

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 17 Effective stress curve of different monitoring points of 2 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

12 Shock and Vibration

protection effectrdquo by water jet slot and wall protectionmaterial are

4 Conclusions

In summary some conclusions can be summarized asfollows

e experiment test on dynamic blast strain was con-ducted and the results indicated that under the combinedeffect of blasthole wall protection material and water jet slotthe blasting strain fields were changed by comparing withthe regular blasthole blasting In the direction of water jetslot the PSPV was increased by 8500 and in the directionperpendicular to the direction of water jet slot the PSPV wasreduced by 7021

Numerical simulation results suggest that the existence ofwater jet slot and blasthole wall protection material can affectthe distribution and evolution law of explosive stress waveand let the stress concentration occur at the tip of water jet

slot which promotes blast-induced crack propagation alongthe specific direction and minimizes the blast-induceddamage of remaining rock mass Moreover the bigger Dmrb is the weaker the ldquoguiding effectrdquo and ldquoblasthole wallprotection effectrdquo by water jet slot and wall protection ma-terial are

Both the experiment test result and the numericalsimulation results indicated that the existence of blastholewall protection material is not only beneficial to the ldquoguidingeffectrdquo of blast-induced crack propagation of water jet slotbut also beneficial to reduce blast-induced damage ofremaining rock mass

Future research work will be focused on the applicationsin practical engineering of this approach

Data Availability

Readers can access the data supporting the conclusions ofthe study by sending a mail to the corresponding author

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 18 Effective stress curve of different monitoring points of 3 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 13

(e-mail dengfengcqu163com) and all data can be cosh-ared without restriction

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

Financial support for this work was provided by the NaturalScience Foundation of Southwest University of Science andTechnology (18zx7124) In particular the authors thank ME D Y Li and M E F W Yan for their kind help inexperimental investigation and sincere suggestion

References

[1] Z N Zhao X T Feng Y X Xiao et al ldquoMicroseismiccharacteristics and rockburst risk of deep tunnel constructedby different excavation methodsrdquo Chinese Journal of Geo-technical Engineering vol 38 no 5 pp 0867ndash0876 2016

[2] Z C Zhang ldquoControl in blasting engineeringrdquo ChineseJournal of Underground Space and Engineering vol 9 no 5pp 1208ndash1214 2013

[3] Y Wang ldquoStudy of the dynamic fracture effect using slottedcartridge decoupling charge blastingrdquo International Journal ofRock Mechanics and Mining Sciences vol 96 pp 34ndash46 2017

[4] S S Rathore and S Bhandari ldquoControlled fracture growth byblasting while protecting damages to remaining rockrdquo RockMechanics and Rock Engineering vol 40 no 3 pp 317ndash3262007

[5] S H Cho Y Nakamura B Mohanty H S Yang andK Kaneko ldquoNumerical study of fracture plane control inlaboratory-scale blastingrdquo Engineering Fracture Mechanicsvol 75 no 13 pp 3966ndash3984 2008

[6] R S Yang Y B Wang and L Y Yang ldquoDynamic causticexperimental study of crack propagation in two borehole cutblastingrdquo Journal of China University of Mining amp Technologyvol 41 no 6 pp 868ndash872 2012

[7] WM Liang X L Yang and Y Q Yu ldquoResearch on theory ondirectional fracture controlled blastingrdquo Journal of LiaoningTechnical University vol 25 no 5 pp 702ndash704 2006

[8] J S Song Y B Wang X T Gao et al ldquoe mechanism ofdirectional fracture controlled blasting and its applicationrdquoJournal of Mining Science and Technology vol 1 no 1pp 16ndash28 2016

[9] Y Wang ldquoExperimental research on the influence of anempty-hole defect on crack connections between a direc-tionally fractured blast holerdquo Journal of Testing and Evalu-ation vol 45 no 6 pp 2139ndash2150 2017

[10] Z Li W Chen and H Hao ldquoNumerical study of sandwichpanel with a new bi-directional load-self-cancelling (LSC)core under blast loadingrdquo =in-Walled Structures vol 127pp 90ndash101 2018

[11] K Katsuyama H Kiyokawa and K Sassa ldquoControl thegrowth of cracks from a borehole by a new method of smoothblastingrdquo Mining Safety vol 29 pp 16ndash23 1983

[12] W L Fourney D B Barker and D C Holloway ldquoModelstudies of explosive well stimulation techniquesrdquo In-ternational Journal of Rock Mechanics and Mining Sciences ampGeomechanics Abstracts vol 18 no 2 pp 113ndash127 1981

[13] W L Fourney D B Barker and D C Holloway ldquoModelstudies of well stimulation using propellant chargesrdquo

International Journal of Rock Mechanics and Mining Sciencesamp Geomechanics Abstracts vol 20 no 2 pp 91ndash101 1983

[14] B Mohanty ldquoExplosive generated fractures in rock and rocklike materialsrdquo Engineering Fracture Mechanics vol 35 no 4-5 pp 889ndash898 1990

[15] B Mohanty ldquoFracture-plane control blasts with satelliteholesrdquo in Proceedings of 3rd International Symposium on RockFragmentation by Blasting pp 407ndash418 Australasian Instituteof Mining and Metallurgy Parkville Australia August 1990

[16] Y G Du Z C Zhang and T L Li ldquoStudies on mechanicaleffect produced by the V-shaped notch borehole blastingrdquoExplosion and Shock Waves vol 11 pp 26ndash30 1991

[17] Q Zong ldquoeoretical study on the cracking mechanism ofnotched borehole blastingrdquo Coal Mine Blasting vol 1pp 12ndash16 1995

[18] Q Zong ldquoInvestigations into mechanism of crack formationfor grooved hole-well blastingrdquo Chinese Journal of Geo-technical Engineering vol 20 no 1 pp 30ndash33 1998

[19] S H Cho Y Nakamura and K Kaneko ldquoDynamic fractureprocess analysis of rock subjected to a stress wave and gaspressurizationrdquo International Journal of Rock Mechanics andMining Sciences vol 41 no 3 pp 433ndash440 2004

[20] Y Zhang ldquoDynamic numerical simulation for the mechanismof V-shaped notch blastingrdquo Explosive Materials vol 38no 4 pp 1ndash5 2009

[21] R S Yang and Y B Wang ldquoDynamic caustic experiment onfracture behaviors of flawed material induced by pre-notchedblastingrdquo Explosive and Shock Waves vol 36 no 2pp 145ndash152 2016

[22] R S Yang C X Ding L Y Yang P Xu and C Chen ldquoHoledefects affect the dynamic fracture behavior of nearby runningcracksrdquo Shock and Vibration vol 2018 Article ID 58943568 pages 2018

[23] Z W Yue Y Guo X Wang et al ldquoInfluence of empty holeshape on directional fracture controlled blasting of rockrdquoRock and Soil Mechanics vol 37 no 2 pp 376ndash382 2016

[24] Z Yue P Qiu R Yang S Zhang K Yuan and Z Li ldquoStressanalysis of the interaction of a running crack and blastingwaves by caustics methodrdquo Engineering Fracture Mechanicsvol 184 pp 339ndash351 2017

[25] B Chen C Liu and J X Yang ldquoAnalysis and application oncontrolling thick hard roof caving with deep-hole positionpresplitting blastingrdquoAdvances in Civil Engineering vol 2018Article ID 9763137 15 pages 2018

[26] Y H Zhu and X P Xu ldquoDamage control characteristics fornotched blasting based on the damage mechanismrdquo Journal ofChina Coal Society vol 42 no 2 pp 369ndash376 2017

[27] X H Li L Yang J S Wang et al ldquoe natural frequencycharacteristic of the self-excited oscillation pulsed water jetdevicerdquo Journal of China Coal Society vol 25 no 6pp 641ndash644 2000

[28] X H Li Y Y Lu Y Zhao et al ldquoStudy on improving thepermeability of soft coal seam with high pressure pulsed waterjetrdquo Journal of China Coal Society vol 33 no 12 pp 1386ndash1390 2007

[29] Y Kang X C Wang X F Yang et al ldquoNumerical simulationof control blasting with borehole protecting and water jetslotting in soft rock massrdquo Disaster Advances vol 5 no 4pp 933ndash938 2012

[30] J-G Kim and J-J Song ldquoAbrasive water jet cutting methodsfor reducing blast-induced ground vibration in tunnel ex-cavationrdquo International Journal of Rock Mechanics andMining Sciences vol 75 pp 147ndash158 2015

14 Shock and Vibration

[31] Y Kang D D Zheng D F Su et al ldquoModel of directionalshaped blasting assisted with water jet and its numericalsimulationrdquo Journal of Vibration and Shock vol 34pp 182ndash188 2015

[32] D Su Y Kang F Yan D Zheng X Wang and M WeildquoCrack propagation law affected by natural fracture and waterjet slot under blast loadingrdquo Combustion Explosion andShock Waves vol 54 no 6 pp 747ndash756 2018

[33] Y B Wang ldquoRock dynamic fracture characteristics based onNSCB impact methodrdquo Shock and Vibration vol 2018 Ar-ticle ID 3105384 13 pages 2018

[34] J Dai Dynamic Behaviors and Blasting =eory of RockMetallurgical Industry Press Beijing China 2013

[35] LSTC LS-DYNAKeyword Userrsquos Manual Livermore SoftwareTechnology Corporation Livermore CA USA 2007

Shock and Vibration 15

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Page 3: ExperimentalStudyandNumericalSimulationofDynamic Stress ...downloads.hindawi.com/journals/sv/2019/1659175.pdf,kLL jLL xLL L xLL jLL,kLL L L©L, L©Lk L©Lff L©Lx _NF ig E NFE #_#YNIkff©,Ifiig

E1-4 test point which shows that when the explosive ex-plodes in a regular blasthole the blasting load almost evenlyworks on the circular blasthole surface [34]

By comparing Figure 5 with Figure 6 we can see that thePSPV value at E2-1 test point is 3667 greater than PSPVat E1-1 test point and the PSPV at E2-2 test point is 179greater than the PSPV at E1-2 test pointat is because thewater jet slot results in stress concentrations along the di-rection of the water jet slot while detonation gases work on

the blasthole surface or stress waves arrive at the tip of thewater jet slot during blasting In addition the positive strainpeak value (PSPV) and mean strain peak value (MSPV) atE1-3 test point and E1-4 test point are almost the same asthe PSPV and MSPV at E2-3 test point and E2-4 testpoint and so as to the evolution law of explosive strainwave It can be seen from the above analysis that the waterjet slot changed the law of stress field distribution duringthe blasting which results in the stress concentrations

Experimental testspecimens

Strain-compensated

Ultra dynamic strainmeasuring systemSignal sensor Data processing

system

Front view

Back view

Figure 2 Diagram of test system connection

If the installation of signal sensor is

properNo

Yes

Installingthe experimental

test specimens

Charging and connecting the

test circuit

Starting the ultra dynamic strain

measuring system

If the connection of test circuit is

proper

Detonating explosive

No

Yes

Test data processing and

analysis

Replace the signal sensor

Replace the test circuit

Figure 3 Diagram of experimental test procedure

Table 1 Parameters of PMMA

Density (gcm3) Poisson ratio Elastic modulus (GPa) Longitudinal wave velocity (cmμs) Shear wave speed (cmμs)12 031 61 23times105 126times107

Shock and Vibration 3

along the direction of the water jet slot However in thedirection perpendicular to water jet slot the existence ofwater jet slot has hardly changed the distribution of stressfield

For 3 test model the existence of blasthole protectionmaterial has greatly changed the distribution law and evo-lution law of the explosive strain wave On one hand thePSPV in the direction of the water jet slot gradually in-creases the PSPV at E2-1 test point is 3667 greater thanthe PSPV at E1-1 test point the PSPV at E3-1 test point is3537 greater than PSPV at E2-1 test point and the PSPVat E3-1 test point is 8500 greater than the PSPV at E1-1test point On the other hand the blasting strain values in thedirection perpendicular to water jet slot respectively de-crease to smaller values Just in regard to the PSPV the figure(623167 με) at E2-3 test point sees a 437 decrease endingup with 350768 με at E3-3 test point and the figures at E2-4 test point and E3-4 test point almost share the samedecreasing proportion It is suggested that in contrast withdirectional-controlled blasting with water jet assistance theexistence of blasthole wall protection material can sharplyreduce the energy of stress wave working on the remainingsides so as to achieve the purpose of protecting the sur-rounding rock

Furthermore by comparing the blasting strain of 2 testmodel and 3 test model we can see that in the direction ofwater jet slot the blast strain is much greater than that in the

direction perpendicular to water jet slot For 2 test modelthe PSPV at E2-1 test point sees a 2836 decrease from869829 με reaching 623167 με at E2-3 test point Besidesfor 3 test model compared with PSPV (1177456 με) at E3-1 test point the PSPV at E3-3 test point falls by 7021ending at 350768 με Both the two decreasing trendsdemonstrate that water jet slot can have an obvious effect onstress concentration along the direction of water jet slot so asto more easily generate perforative fractures along this di-rection during blasting and the remaining rock can be betterprotected

To sum up some conclusions can be summarized fromthe experimental test as follows

(1) Under the combined effect of blasthole wall pro-tection material and water jet slot the PSPV bycomparing with regular blasthole blasting was in-creased by 8500 in the direction of water jet slotand the PSPV in the direction perpendicular to thedirection of water jet slot was reduced by 7021

(2) In contrast with directional-controlled blasting withwater jet assistance the existence of blasthole wallprotection material is not only beneficial to theldquoguiding effectrdquo of blast-induced crack propagationof water jet slot but also beneficial to reduce blast-induced damage of remaining rock mass

Regular blasthole

2

E1-4

E1-3

E1-1 E1-24

(a)

Water jet slotted blasthole

2

E2-1 E2-24

E2-4

E2-3

(b)

Water jet slotted blastholewith wall protection material

E3-4

E3-3

2

E3-1 E3-2

4

(c)

Figure 4 Sketches of three different blasting models and the strain gauge arrangement (a) 1 test model (b) 2 test model and (c) 3 testmodel

Table 2 Strain values for three different blasting models

Test model Strain valueValues (με)

Channel 1 Channel 2 Channel 3 Channel 4

Model 1Positive strain peak value 636454 537698 672342 570690Negative strain peak value minus495945 minus248893 minus722151 minus396569Mean strain peak value 83223 73074 92998 78041

Model 2Positive strain peak value 869829 633962 623167 520278Negative strain peak value minus341492 minus280124 minus718531 minus388996Mean strain peak value 171153 132421 80121 63676

Model 3Positive strain peak value 1177456 810468 350768 295034Negative strain peak value minus772859 minus348843 minus368530 minus271644Mean strain peak value 224876 189897 27480 12654

4 Shock and Vibration

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 636454μεNSPV ndash495945μεMSPV 83223με

(a)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 537698μεNSPV ndash248893μεMSPV 73074με

(b)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 672342μεNSPV ndash722151μεMSPV 92998με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 570690μεNSPV ndash396569μεMSPV 78041με

(d)

Figure 5 Waveform curve of dynamic strain for 1 test model (a) E1-1 test point (b) E1-2 test point (c) E1-3 test point and (d) E1-4test point

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 869829μεNSPV ndash341492μεMSPV 171153με

(a)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 633962μεNSPV ndash280124μεMSPV 132421με

(b)

Figure 6 Continued

Shock and Vibration 5

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 623167μεNSPV ndash718531μεMSPV 80121με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 520278μεNSPV ndash388996μεMSPV 63676με

(d)

Figure 6 Waveform curve of dynamic strain for 2 test model (a) E2-1 test point (b) E2-2 test point (c) E2-3 test point and (d) E2-4test point

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 1177456μεNSPV ndash772859μεMSPV 224876με

(a)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 810468μεNSPV ndash348843μεMSPV 189897με

(b)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 350768μεNSPV ndash368530μεMSPV 27480με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 295034μεNSPV ndash271644μεMSPV 12654με

(d)

Figure 7 Waveform curve of dynamic strain for 3 test model (a) E3-1 test point (b) E3-2 test point (c) E3-3 test point and (d) E3-4test point

6 Shock and Vibration

3 Numerical Simulation of BlastStress Evolution

e FEM software ANSYSLS-DYNA and the post-processing software LS-PREPOST were applied to in-vestigate the blasting stress wave evolution law and the blast-induced crack propagation law for different conditions

31 Numerical Simulation Model ree simulation caseswere conducted by ANSYSLS-DYNA Due to the symmetryof the simulated object both simulation cases applied aquasi-2D simulation model For each case the size of rock is150 cmtimes 150 cmtimes 03 cm the diameter of blasthole is 5 cmthe thickness of the blasthole wall protection material is05 cm and the size of the water jet slot is25 cmtimes 05 cmtimes 03 cm e 3 simulation model is shownin Figure 8

32 Material Model

321 Rock Material type 3 of LS-DYNA (lowastMAT_PLASTIC_KINEMATIC) was applied to model the rock [35] and itsparameters are shown in Table 3

322 BlastholeWall ProtectionMaterial Material type 3 ofLS-DYNA (lowastMAT_PLASTIC_KINEMATIC) was applied tomodel the blasthole wall protection material [35] and itsparameters are shown in Table 4

323 Explosive Material type 8 of LS-DYNA(lowastMAT_HIGH_EXPLOSIVE_BURN) was chosen as theexplosive model and the pressure released by the chemicalenergy in the engineering calculations was modelled by theJonesndashWilkinsndashLee equation of state e JWL EOS can bewritten in the following form [35]

Pe A 1minusω

R1V1113888 1113889e

minusR1V+ B 1minus

ωR2V

1113888 1113889eminusR2V

+ωEe

V (1)

where Pe is the pressure produced by the detonationproducts from explosive where ω A B R1 and R2 are user-defined input parameters V is the relative volume and Ee isthe internal energy per initial volume as shown in Table 5

324 Air Air was modelled by the material type 9 of LS-DYNA (lowastMAT_NULL) with the Gruneisen equation epressure Pa can be calculated by [35]

Pa C0 + C1μ + C2μ2 + C3μ3 + C4 + C5μ + C6μ2( 1113857Ea

μ 1

Vaminus 1

⎧⎪⎪⎪⎪⎨

⎪⎪⎪⎪⎩

(2)

where C0 C1 C2 C3 C4 C5 and C6 are user-definedconstants ρa is the density of air Va is the relative

volume of air Ea is the internal energy of air as shown inTable 6

33 Numerical Calculation Algorithm Lagrange algorithmhas the priority of less computation time and accuratelydescribing the boundary movement of structure so it isalways used to analyze the explosive detonation Howeverit has a big disadvantage of causing element distortion andeven leads to the termination of calculation when dealingwith the large deformation numerical calculation Inorder to avoid the above problem fluid-solid couplingalgorithm was adopted for the analysis of the explosivedetonation of which ALE algorithm was used for ex-plosive and air and Lagrange algorithm for rock andprotecting pipe e material derivative equation and thegoverning equations of the ALE algorithm can beexpressed as follows [35]

df(X t)

dt

zf(ξ t)

zt+ vi minuswi( 1113857

zf(x t)

zxi

zρzt

ρzυi

zx+ ωi

zρzx

ρzυi

zt+ ρωi

zυi

zxj

zσij

zxj

+ ρfi

ρze

zt σij

zυi

zxj

minuszq

zxj

minus ρωi

ze

zxi

(3)

where f is the physical quantity vi is the velocity of particleX ωi is the velocity of the computational grid xi is theLagrangian coordinate system yi is the Eulerian coordinatesystem ρ is the density v is the particle velocity e is theinternal energy of unit mass σij is the Cauchy stress tensorfi is the body force qi is the heat flux and subscripts i and j

stand for the direction of coordinateAt the same time meshes of explosive and the air were

joined with common nodes and so as to rock and protectingpipe en the fluid-solid coupling was defined between themeshes of the explosive air rock and protecting pipe by thekeyword In addition according to the characteristics ofblasting process the time step of the simulation is 067 andthe computation time is 0004 s

34 Simulation Results Analysis e Postprocessing soft-ware LS-PREPOST was used to draw the diagrams of theevolution law of explosion stress wave and crack propaga-tion of different simulation cases as shown in Figures 9ndash11

In general for regular blasthole blasting the explosionstress uniformly acts on the wall of blasthole and the shapeof blast stress wave is round and then the blast-inducedcrack forms and expands under the blast loading Due to thecharacters of blast loading the gas pressure acting onblasthole wall in all directions can be considered as equiv-alent so the well-distributed blast-induced cracks generatenear the blasthole which is consistent with the classicalblasting theory

Shock and Vibration 7

However by comparing 1 simulation case the blast-induced crack propagation law and the transmission law ofexplosion stress wave of 2 simulation case and 3 simu-lation case were greatly changed under the effect of water jetslot and blasthole wall protection materials On one handblasting energy focus forms at the initial stage of the ex-plosion which promotes the initial microcrack produced atthe direction of water jet slot And nothing but air is in thewater jet slot which caused the formation of low-pressurezone so detonation products have priority to flow along thedirection of water jet slot en the high-pressure and high-velocity gas products wedge into the slot further leading tocrack initiation and extension along the desired direction asshown in Figures 10 and 11 On the other hand as the failureof blasthole wall protectionmaterial makes a large amount ofconsumption of blast energy the formation of microcrack ofthe remaining rock mass was restrained Furthermorethe blasthole wall protection material is in a molten stateduring the blasting which will wedge into the unexpected

microcracks and then the ldquogas edge effectrdquo of gas productwill be greatly weakened So the dual purpose of directionalblast-induced crack propagation and remaining rock massprotection is realized

To further understand the transmission law of blaststress wave and the change regularity of blasting strain underdifferent conditions monitoring points were set in thenumerical simulation model and its schematic diagram isshown in Figure 12 where Dm stands for the distance be-tween the monitoring point and the center of blasthole rbstands for the radius of blasthole and αn is the angle betweentwo lines one is the connection between blasthole center andwater jet slot and the another is the connection betweenblasthole center and monitoring point

Figures 13ndash15 show the P-T curves of different simu-lation cases from which we can see that with the increase ofDm the pressure of different cases almost shows a trend ofgradual decrease but the pressure of different monitoringpoints of different cases shows a different changing trendFor 1 simulation case when Dmrb is certain each P-Tcurve shows the same trend because of the explosion at isbecause the explosion stress uniformly acts on the wall ofblasthole during blasting which is consistent with experi-ment test result For 2 simulation case when αn is 0deg the

Table 3 Parameters of rock

Density (gcm3) Elastic modulus (MPa) Tangent modulus (MPa) Poisson ratio Yield strength (MPa) SRC SRP Failure strain250 225times104 420times103 022 300 0 0 006

Table 4 Parameters of blasthole wall protection material

Density (gcm3) Elastic modulus (MPa) Poisson ratio Yield strength (MPa) SRC SRP Failure strain143 300times103 03 18times10minus1 0 0 01

Table 5 Parameters of explosive and its EOS equation

ρe (gcm3) vD (cmμs) Pcut (MPa) A (MPa) B (MPa) R1 R2 ω

170 083 295times104 855times105 205times104 460 135 025

Table 6 Parameters of air and its EOS equation

ρa (gcm3) C0 C1 C2 C3 C4 C5 C6

120times10minus3 000 000 000 000 040 040 000

Nonreflected boundaryRock

Nonreflected boundary

A

75

150

150

75

Blasthole wall protection material

Explosive

Water jet slot

(a) (b)

Figure 8 Numerical simulation model (a) 3 simulation model (b) enlargement of part A

8 Shock and Vibration

peak value of the measuring point is smaller than that ofregular blasting but the valley value is bigger than that ofregular blasthole blasting at is to say the rock will besubjected to tensile stress As we know the tensile strength ofrock is far less than its compressive strength so the rock isvulnerable to failure [34] which suggest that the existence ofthe water jet slot changed the distribution laws of stress fieldsduring blasting let the blast-induced crack initiation andpropagation in the direction of water jet slot

For 3 simulation case when αn is 0deg though the peakvalue continues to decline valley value is 4040 greaterthan that of 2 simulation case Moreover the action time of

tensile stress of 3 simulation case is much longer than thatof 2 simulation case When αn is 90deg the peak value is2534 and 2966 smaller than that of 2 simulation caseand 1 simulation case respectively which demonstratesthat the existence of blasthole wall protection material hascreated more favorable conditions for the blast-inducedcrack propagation along the direction of water jet slotand the protection of blasthole wall during blasting which isconsistent with the above analysis

Figures 16ndash18 present the effective stress curves of dif-ferent simulation cases For 1 simulation case as the ex-plosion stress uniformly acts on the wall of blasthole during

Blast stress wave Blast-induced crack

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 9 Diagram of blast-induced crack propagation and stress wave transmission of 1 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focus Blast-induced crack

Stress concentration

Blast stress wave

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 10 Diagram of blast-induced crack propagation and stress wave transmission of 2 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focusBlast-induced crack

Stress concentration

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 11 Diagram of blast-induced crack propagation and stress wave transmission of 3 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Shock and Vibration 9

αn

N2-4

N2-3

N2-2

N2-1

N1-110 10 1020

N1-2 N1-3 N1-4

90deg

Dm

rb

Figure 12 Schematic diagram of monitoring point layout

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 13 P-T curve of different monitoring points of 1 simulation case (a) αn 0deg (b) αn 90deg

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

(b)

Figure 14 P-T curve of different monitoring points of 2 simulation case (a) αn 0deg (b) αn 90deg

10 Shock and Vibration

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 15 P-T curve of different monitoring points of 3 simulation case (a) αn 0deg (b) αn 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(b)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(c)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(d)

Figure 16 Effective stress curve of different monitoring points of 1 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 11

blasting the effective stress of each curve shows the sametrend if Dmrb is certain and the effective stress decreasesgradually and becomes stable with the increase of Dmrb For2 simulation case the peak value of effective stress de-creases with the increase of Dmrb and αn at is to say ifDmrb is certain the rock located at different directionsaround the blasthole suffered different effective stress thecloser the rock gets to the direction of water jet the biggerthe effective stress the rock suffered For 3 simulation casethe variation trend of effective stress is similar to that of 2simulation case but the peak value of each effective stresscurve is quite different By comparing each effective stresscurve of 2 simulation case and 3 simulation case we cansee that in the direction of water jet slot the peak value ofeffective stress of 3 simulation case is always bigger thanthat of 2 simulation case However in the direction per-pendicular to the direction of the jet slot the peak value ofeffective stress of 3 simulation case is always smaller than

that of 2 simulation case which indicates that the existenceof blasthole wall protection material is not only very ben-eficial to the ldquoguiding effectrdquo of blast-induced crack prop-agation by water jet slot but also beneficial to reduce blast-induced damage of remaining rock mass

Moreover by comparing Figures 16(d) 17(d) and 18(d)we can see that in the direction of water jet slot the effectivestress of 2 simulation case decreases gradually and whenDmrb is 20 the distribution-evolution law of effective stressis similar to that of 1 simulation case However for 3simulation case when Dmrb is 20 the peak value of effectivestress is bigger than that of 2 simulation case and thegrowing trend of effective stress shows a large fluctuationwhich suggested that the rock suffered the ldquoguiding effectrdquo bywater jet slot In addition in the other direction of blastholethe distribution-evolution law of effective stress is similar tothat of 1 simulation case at is to say the bigger Dmrb isthe weaker the ldquoguiding effectrdquo and ldquoblasthole wall

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 17 Effective stress curve of different monitoring points of 2 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

12 Shock and Vibration

protection effectrdquo by water jet slot and wall protectionmaterial are

4 Conclusions

In summary some conclusions can be summarized asfollows

e experiment test on dynamic blast strain was con-ducted and the results indicated that under the combinedeffect of blasthole wall protection material and water jet slotthe blasting strain fields were changed by comparing withthe regular blasthole blasting In the direction of water jetslot the PSPV was increased by 8500 and in the directionperpendicular to the direction of water jet slot the PSPV wasreduced by 7021

Numerical simulation results suggest that the existence ofwater jet slot and blasthole wall protection material can affectthe distribution and evolution law of explosive stress waveand let the stress concentration occur at the tip of water jet

slot which promotes blast-induced crack propagation alongthe specific direction and minimizes the blast-induceddamage of remaining rock mass Moreover the bigger Dmrb is the weaker the ldquoguiding effectrdquo and ldquoblasthole wallprotection effectrdquo by water jet slot and wall protection ma-terial are

Both the experiment test result and the numericalsimulation results indicated that the existence of blastholewall protection material is not only beneficial to the ldquoguidingeffectrdquo of blast-induced crack propagation of water jet slotbut also beneficial to reduce blast-induced damage ofremaining rock mass

Future research work will be focused on the applicationsin practical engineering of this approach

Data Availability

Readers can access the data supporting the conclusions ofthe study by sending a mail to the corresponding author

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 18 Effective stress curve of different monitoring points of 3 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 13

(e-mail dengfengcqu163com) and all data can be cosh-ared without restriction

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

Financial support for this work was provided by the NaturalScience Foundation of Southwest University of Science andTechnology (18zx7124) In particular the authors thank ME D Y Li and M E F W Yan for their kind help inexperimental investigation and sincere suggestion

References

[1] Z N Zhao X T Feng Y X Xiao et al ldquoMicroseismiccharacteristics and rockburst risk of deep tunnel constructedby different excavation methodsrdquo Chinese Journal of Geo-technical Engineering vol 38 no 5 pp 0867ndash0876 2016

[2] Z C Zhang ldquoControl in blasting engineeringrdquo ChineseJournal of Underground Space and Engineering vol 9 no 5pp 1208ndash1214 2013

[3] Y Wang ldquoStudy of the dynamic fracture effect using slottedcartridge decoupling charge blastingrdquo International Journal ofRock Mechanics and Mining Sciences vol 96 pp 34ndash46 2017

[4] S S Rathore and S Bhandari ldquoControlled fracture growth byblasting while protecting damages to remaining rockrdquo RockMechanics and Rock Engineering vol 40 no 3 pp 317ndash3262007

[5] S H Cho Y Nakamura B Mohanty H S Yang andK Kaneko ldquoNumerical study of fracture plane control inlaboratory-scale blastingrdquo Engineering Fracture Mechanicsvol 75 no 13 pp 3966ndash3984 2008

[6] R S Yang Y B Wang and L Y Yang ldquoDynamic causticexperimental study of crack propagation in two borehole cutblastingrdquo Journal of China University of Mining amp Technologyvol 41 no 6 pp 868ndash872 2012

[7] WM Liang X L Yang and Y Q Yu ldquoResearch on theory ondirectional fracture controlled blastingrdquo Journal of LiaoningTechnical University vol 25 no 5 pp 702ndash704 2006

[8] J S Song Y B Wang X T Gao et al ldquoe mechanism ofdirectional fracture controlled blasting and its applicationrdquoJournal of Mining Science and Technology vol 1 no 1pp 16ndash28 2016

[9] Y Wang ldquoExperimental research on the influence of anempty-hole defect on crack connections between a direc-tionally fractured blast holerdquo Journal of Testing and Evalu-ation vol 45 no 6 pp 2139ndash2150 2017

[10] Z Li W Chen and H Hao ldquoNumerical study of sandwichpanel with a new bi-directional load-self-cancelling (LSC)core under blast loadingrdquo =in-Walled Structures vol 127pp 90ndash101 2018

[11] K Katsuyama H Kiyokawa and K Sassa ldquoControl thegrowth of cracks from a borehole by a new method of smoothblastingrdquo Mining Safety vol 29 pp 16ndash23 1983

[12] W L Fourney D B Barker and D C Holloway ldquoModelstudies of explosive well stimulation techniquesrdquo In-ternational Journal of Rock Mechanics and Mining Sciences ampGeomechanics Abstracts vol 18 no 2 pp 113ndash127 1981

[13] W L Fourney D B Barker and D C Holloway ldquoModelstudies of well stimulation using propellant chargesrdquo

International Journal of Rock Mechanics and Mining Sciencesamp Geomechanics Abstracts vol 20 no 2 pp 91ndash101 1983

[14] B Mohanty ldquoExplosive generated fractures in rock and rocklike materialsrdquo Engineering Fracture Mechanics vol 35 no 4-5 pp 889ndash898 1990

[15] B Mohanty ldquoFracture-plane control blasts with satelliteholesrdquo in Proceedings of 3rd International Symposium on RockFragmentation by Blasting pp 407ndash418 Australasian Instituteof Mining and Metallurgy Parkville Australia August 1990

[16] Y G Du Z C Zhang and T L Li ldquoStudies on mechanicaleffect produced by the V-shaped notch borehole blastingrdquoExplosion and Shock Waves vol 11 pp 26ndash30 1991

[17] Q Zong ldquoeoretical study on the cracking mechanism ofnotched borehole blastingrdquo Coal Mine Blasting vol 1pp 12ndash16 1995

[18] Q Zong ldquoInvestigations into mechanism of crack formationfor grooved hole-well blastingrdquo Chinese Journal of Geo-technical Engineering vol 20 no 1 pp 30ndash33 1998

[19] S H Cho Y Nakamura and K Kaneko ldquoDynamic fractureprocess analysis of rock subjected to a stress wave and gaspressurizationrdquo International Journal of Rock Mechanics andMining Sciences vol 41 no 3 pp 433ndash440 2004

[20] Y Zhang ldquoDynamic numerical simulation for the mechanismof V-shaped notch blastingrdquo Explosive Materials vol 38no 4 pp 1ndash5 2009

[21] R S Yang and Y B Wang ldquoDynamic caustic experiment onfracture behaviors of flawed material induced by pre-notchedblastingrdquo Explosive and Shock Waves vol 36 no 2pp 145ndash152 2016

[22] R S Yang C X Ding L Y Yang P Xu and C Chen ldquoHoledefects affect the dynamic fracture behavior of nearby runningcracksrdquo Shock and Vibration vol 2018 Article ID 58943568 pages 2018

[23] Z W Yue Y Guo X Wang et al ldquoInfluence of empty holeshape on directional fracture controlled blasting of rockrdquoRock and Soil Mechanics vol 37 no 2 pp 376ndash382 2016

[24] Z Yue P Qiu R Yang S Zhang K Yuan and Z Li ldquoStressanalysis of the interaction of a running crack and blastingwaves by caustics methodrdquo Engineering Fracture Mechanicsvol 184 pp 339ndash351 2017

[25] B Chen C Liu and J X Yang ldquoAnalysis and application oncontrolling thick hard roof caving with deep-hole positionpresplitting blastingrdquoAdvances in Civil Engineering vol 2018Article ID 9763137 15 pages 2018

[26] Y H Zhu and X P Xu ldquoDamage control characteristics fornotched blasting based on the damage mechanismrdquo Journal ofChina Coal Society vol 42 no 2 pp 369ndash376 2017

[27] X H Li L Yang J S Wang et al ldquoe natural frequencycharacteristic of the self-excited oscillation pulsed water jetdevicerdquo Journal of China Coal Society vol 25 no 6pp 641ndash644 2000

[28] X H Li Y Y Lu Y Zhao et al ldquoStudy on improving thepermeability of soft coal seam with high pressure pulsed waterjetrdquo Journal of China Coal Society vol 33 no 12 pp 1386ndash1390 2007

[29] Y Kang X C Wang X F Yang et al ldquoNumerical simulationof control blasting with borehole protecting and water jetslotting in soft rock massrdquo Disaster Advances vol 5 no 4pp 933ndash938 2012

[30] J-G Kim and J-J Song ldquoAbrasive water jet cutting methodsfor reducing blast-induced ground vibration in tunnel ex-cavationrdquo International Journal of Rock Mechanics andMining Sciences vol 75 pp 147ndash158 2015

14 Shock and Vibration

[31] Y Kang D D Zheng D F Su et al ldquoModel of directionalshaped blasting assisted with water jet and its numericalsimulationrdquo Journal of Vibration and Shock vol 34pp 182ndash188 2015

[32] D Su Y Kang F Yan D Zheng X Wang and M WeildquoCrack propagation law affected by natural fracture and waterjet slot under blast loadingrdquo Combustion Explosion andShock Waves vol 54 no 6 pp 747ndash756 2018

[33] Y B Wang ldquoRock dynamic fracture characteristics based onNSCB impact methodrdquo Shock and Vibration vol 2018 Ar-ticle ID 3105384 13 pages 2018

[34] J Dai Dynamic Behaviors and Blasting =eory of RockMetallurgical Industry Press Beijing China 2013

[35] LSTC LS-DYNAKeyword Userrsquos Manual Livermore SoftwareTechnology Corporation Livermore CA USA 2007

Shock and Vibration 15

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Page 4: ExperimentalStudyandNumericalSimulationofDynamic Stress ...downloads.hindawi.com/journals/sv/2019/1659175.pdf,kLL jLL xLL L xLL jLL,kLL L L©L, L©Lk L©Lff L©Lx _NF ig E NFE #_#YNIkff©,Ifiig

along the direction of the water jet slot However in thedirection perpendicular to water jet slot the existence ofwater jet slot has hardly changed the distribution of stressfield

For 3 test model the existence of blasthole protectionmaterial has greatly changed the distribution law and evo-lution law of the explosive strain wave On one hand thePSPV in the direction of the water jet slot gradually in-creases the PSPV at E2-1 test point is 3667 greater thanthe PSPV at E1-1 test point the PSPV at E3-1 test point is3537 greater than PSPV at E2-1 test point and the PSPVat E3-1 test point is 8500 greater than the PSPV at E1-1test point On the other hand the blasting strain values in thedirection perpendicular to water jet slot respectively de-crease to smaller values Just in regard to the PSPV the figure(623167 με) at E2-3 test point sees a 437 decrease endingup with 350768 με at E3-3 test point and the figures at E2-4 test point and E3-4 test point almost share the samedecreasing proportion It is suggested that in contrast withdirectional-controlled blasting with water jet assistance theexistence of blasthole wall protection material can sharplyreduce the energy of stress wave working on the remainingsides so as to achieve the purpose of protecting the sur-rounding rock

Furthermore by comparing the blasting strain of 2 testmodel and 3 test model we can see that in the direction ofwater jet slot the blast strain is much greater than that in the

direction perpendicular to water jet slot For 2 test modelthe PSPV at E2-1 test point sees a 2836 decrease from869829 με reaching 623167 με at E2-3 test point Besidesfor 3 test model compared with PSPV (1177456 με) at E3-1 test point the PSPV at E3-3 test point falls by 7021ending at 350768 με Both the two decreasing trendsdemonstrate that water jet slot can have an obvious effect onstress concentration along the direction of water jet slot so asto more easily generate perforative fractures along this di-rection during blasting and the remaining rock can be betterprotected

To sum up some conclusions can be summarized fromthe experimental test as follows

(1) Under the combined effect of blasthole wall pro-tection material and water jet slot the PSPV bycomparing with regular blasthole blasting was in-creased by 8500 in the direction of water jet slotand the PSPV in the direction perpendicular to thedirection of water jet slot was reduced by 7021

(2) In contrast with directional-controlled blasting withwater jet assistance the existence of blasthole wallprotection material is not only beneficial to theldquoguiding effectrdquo of blast-induced crack propagationof water jet slot but also beneficial to reduce blast-induced damage of remaining rock mass

Regular blasthole

2

E1-4

E1-3

E1-1 E1-24

(a)

Water jet slotted blasthole

2

E2-1 E2-24

E2-4

E2-3

(b)

Water jet slotted blastholewith wall protection material

E3-4

E3-3

2

E3-1 E3-2

4

(c)

Figure 4 Sketches of three different blasting models and the strain gauge arrangement (a) 1 test model (b) 2 test model and (c) 3 testmodel

Table 2 Strain values for three different blasting models

Test model Strain valueValues (με)

Channel 1 Channel 2 Channel 3 Channel 4

Model 1Positive strain peak value 636454 537698 672342 570690Negative strain peak value minus495945 minus248893 minus722151 minus396569Mean strain peak value 83223 73074 92998 78041

Model 2Positive strain peak value 869829 633962 623167 520278Negative strain peak value minus341492 minus280124 minus718531 minus388996Mean strain peak value 171153 132421 80121 63676

Model 3Positive strain peak value 1177456 810468 350768 295034Negative strain peak value minus772859 minus348843 minus368530 minus271644Mean strain peak value 224876 189897 27480 12654

4 Shock and Vibration

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 636454μεNSPV ndash495945μεMSPV 83223με

(a)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 537698μεNSPV ndash248893μεMSPV 73074με

(b)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 672342μεNSPV ndash722151μεMSPV 92998με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 570690μεNSPV ndash396569μεMSPV 78041με

(d)

Figure 5 Waveform curve of dynamic strain for 1 test model (a) E1-1 test point (b) E1-2 test point (c) E1-3 test point and (d) E1-4test point

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 869829μεNSPV ndash341492μεMSPV 171153με

(a)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 633962μεNSPV ndash280124μεMSPV 132421με

(b)

Figure 6 Continued

Shock and Vibration 5

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 623167μεNSPV ndash718531μεMSPV 80121με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 520278μεNSPV ndash388996μεMSPV 63676με

(d)

Figure 6 Waveform curve of dynamic strain for 2 test model (a) E2-1 test point (b) E2-2 test point (c) E2-3 test point and (d) E2-4test point

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 1177456μεNSPV ndash772859μεMSPV 224876με

(a)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 810468μεNSPV ndash348843μεMSPV 189897με

(b)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 350768μεNSPV ndash368530μεMSPV 27480με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 295034μεNSPV ndash271644μεMSPV 12654με

(d)

Figure 7 Waveform curve of dynamic strain for 3 test model (a) E3-1 test point (b) E3-2 test point (c) E3-3 test point and (d) E3-4test point

6 Shock and Vibration

3 Numerical Simulation of BlastStress Evolution

e FEM software ANSYSLS-DYNA and the post-processing software LS-PREPOST were applied to in-vestigate the blasting stress wave evolution law and the blast-induced crack propagation law for different conditions

31 Numerical Simulation Model ree simulation caseswere conducted by ANSYSLS-DYNA Due to the symmetryof the simulated object both simulation cases applied aquasi-2D simulation model For each case the size of rock is150 cmtimes 150 cmtimes 03 cm the diameter of blasthole is 5 cmthe thickness of the blasthole wall protection material is05 cm and the size of the water jet slot is25 cmtimes 05 cmtimes 03 cm e 3 simulation model is shownin Figure 8

32 Material Model

321 Rock Material type 3 of LS-DYNA (lowastMAT_PLASTIC_KINEMATIC) was applied to model the rock [35] and itsparameters are shown in Table 3

322 BlastholeWall ProtectionMaterial Material type 3 ofLS-DYNA (lowastMAT_PLASTIC_KINEMATIC) was applied tomodel the blasthole wall protection material [35] and itsparameters are shown in Table 4

323 Explosive Material type 8 of LS-DYNA(lowastMAT_HIGH_EXPLOSIVE_BURN) was chosen as theexplosive model and the pressure released by the chemicalenergy in the engineering calculations was modelled by theJonesndashWilkinsndashLee equation of state e JWL EOS can bewritten in the following form [35]

Pe A 1minusω

R1V1113888 1113889e

minusR1V+ B 1minus

ωR2V

1113888 1113889eminusR2V

+ωEe

V (1)

where Pe is the pressure produced by the detonationproducts from explosive where ω A B R1 and R2 are user-defined input parameters V is the relative volume and Ee isthe internal energy per initial volume as shown in Table 5

324 Air Air was modelled by the material type 9 of LS-DYNA (lowastMAT_NULL) with the Gruneisen equation epressure Pa can be calculated by [35]

Pa C0 + C1μ + C2μ2 + C3μ3 + C4 + C5μ + C6μ2( 1113857Ea

μ 1

Vaminus 1

⎧⎪⎪⎪⎪⎨

⎪⎪⎪⎪⎩

(2)

where C0 C1 C2 C3 C4 C5 and C6 are user-definedconstants ρa is the density of air Va is the relative

volume of air Ea is the internal energy of air as shown inTable 6

33 Numerical Calculation Algorithm Lagrange algorithmhas the priority of less computation time and accuratelydescribing the boundary movement of structure so it isalways used to analyze the explosive detonation Howeverit has a big disadvantage of causing element distortion andeven leads to the termination of calculation when dealingwith the large deformation numerical calculation Inorder to avoid the above problem fluid-solid couplingalgorithm was adopted for the analysis of the explosivedetonation of which ALE algorithm was used for ex-plosive and air and Lagrange algorithm for rock andprotecting pipe e material derivative equation and thegoverning equations of the ALE algorithm can beexpressed as follows [35]

df(X t)

dt

zf(ξ t)

zt+ vi minuswi( 1113857

zf(x t)

zxi

zρzt

ρzυi

zx+ ωi

zρzx

ρzυi

zt+ ρωi

zυi

zxj

zσij

zxj

+ ρfi

ρze

zt σij

zυi

zxj

minuszq

zxj

minus ρωi

ze

zxi

(3)

where f is the physical quantity vi is the velocity of particleX ωi is the velocity of the computational grid xi is theLagrangian coordinate system yi is the Eulerian coordinatesystem ρ is the density v is the particle velocity e is theinternal energy of unit mass σij is the Cauchy stress tensorfi is the body force qi is the heat flux and subscripts i and j

stand for the direction of coordinateAt the same time meshes of explosive and the air were

joined with common nodes and so as to rock and protectingpipe en the fluid-solid coupling was defined between themeshes of the explosive air rock and protecting pipe by thekeyword In addition according to the characteristics ofblasting process the time step of the simulation is 067 andthe computation time is 0004 s

34 Simulation Results Analysis e Postprocessing soft-ware LS-PREPOST was used to draw the diagrams of theevolution law of explosion stress wave and crack propaga-tion of different simulation cases as shown in Figures 9ndash11

In general for regular blasthole blasting the explosionstress uniformly acts on the wall of blasthole and the shapeof blast stress wave is round and then the blast-inducedcrack forms and expands under the blast loading Due to thecharacters of blast loading the gas pressure acting onblasthole wall in all directions can be considered as equiv-alent so the well-distributed blast-induced cracks generatenear the blasthole which is consistent with the classicalblasting theory

Shock and Vibration 7

However by comparing 1 simulation case the blast-induced crack propagation law and the transmission law ofexplosion stress wave of 2 simulation case and 3 simu-lation case were greatly changed under the effect of water jetslot and blasthole wall protection materials On one handblasting energy focus forms at the initial stage of the ex-plosion which promotes the initial microcrack produced atthe direction of water jet slot And nothing but air is in thewater jet slot which caused the formation of low-pressurezone so detonation products have priority to flow along thedirection of water jet slot en the high-pressure and high-velocity gas products wedge into the slot further leading tocrack initiation and extension along the desired direction asshown in Figures 10 and 11 On the other hand as the failureof blasthole wall protectionmaterial makes a large amount ofconsumption of blast energy the formation of microcrack ofthe remaining rock mass was restrained Furthermorethe blasthole wall protection material is in a molten stateduring the blasting which will wedge into the unexpected

microcracks and then the ldquogas edge effectrdquo of gas productwill be greatly weakened So the dual purpose of directionalblast-induced crack propagation and remaining rock massprotection is realized

To further understand the transmission law of blaststress wave and the change regularity of blasting strain underdifferent conditions monitoring points were set in thenumerical simulation model and its schematic diagram isshown in Figure 12 where Dm stands for the distance be-tween the monitoring point and the center of blasthole rbstands for the radius of blasthole and αn is the angle betweentwo lines one is the connection between blasthole center andwater jet slot and the another is the connection betweenblasthole center and monitoring point

Figures 13ndash15 show the P-T curves of different simu-lation cases from which we can see that with the increase ofDm the pressure of different cases almost shows a trend ofgradual decrease but the pressure of different monitoringpoints of different cases shows a different changing trendFor 1 simulation case when Dmrb is certain each P-Tcurve shows the same trend because of the explosion at isbecause the explosion stress uniformly acts on the wall ofblasthole during blasting which is consistent with experi-ment test result For 2 simulation case when αn is 0deg the

Table 3 Parameters of rock

Density (gcm3) Elastic modulus (MPa) Tangent modulus (MPa) Poisson ratio Yield strength (MPa) SRC SRP Failure strain250 225times104 420times103 022 300 0 0 006

Table 4 Parameters of blasthole wall protection material

Density (gcm3) Elastic modulus (MPa) Poisson ratio Yield strength (MPa) SRC SRP Failure strain143 300times103 03 18times10minus1 0 0 01

Table 5 Parameters of explosive and its EOS equation

ρe (gcm3) vD (cmμs) Pcut (MPa) A (MPa) B (MPa) R1 R2 ω

170 083 295times104 855times105 205times104 460 135 025

Table 6 Parameters of air and its EOS equation

ρa (gcm3) C0 C1 C2 C3 C4 C5 C6

120times10minus3 000 000 000 000 040 040 000

Nonreflected boundaryRock

Nonreflected boundary

A

75

150

150

75

Blasthole wall protection material

Explosive

Water jet slot

(a) (b)

Figure 8 Numerical simulation model (a) 3 simulation model (b) enlargement of part A

8 Shock and Vibration

peak value of the measuring point is smaller than that ofregular blasting but the valley value is bigger than that ofregular blasthole blasting at is to say the rock will besubjected to tensile stress As we know the tensile strength ofrock is far less than its compressive strength so the rock isvulnerable to failure [34] which suggest that the existence ofthe water jet slot changed the distribution laws of stress fieldsduring blasting let the blast-induced crack initiation andpropagation in the direction of water jet slot

For 3 simulation case when αn is 0deg though the peakvalue continues to decline valley value is 4040 greaterthan that of 2 simulation case Moreover the action time of

tensile stress of 3 simulation case is much longer than thatof 2 simulation case When αn is 90deg the peak value is2534 and 2966 smaller than that of 2 simulation caseand 1 simulation case respectively which demonstratesthat the existence of blasthole wall protection material hascreated more favorable conditions for the blast-inducedcrack propagation along the direction of water jet slotand the protection of blasthole wall during blasting which isconsistent with the above analysis

Figures 16ndash18 present the effective stress curves of dif-ferent simulation cases For 1 simulation case as the ex-plosion stress uniformly acts on the wall of blasthole during

Blast stress wave Blast-induced crack

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 9 Diagram of blast-induced crack propagation and stress wave transmission of 1 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focus Blast-induced crack

Stress concentration

Blast stress wave

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 10 Diagram of blast-induced crack propagation and stress wave transmission of 2 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focusBlast-induced crack

Stress concentration

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 11 Diagram of blast-induced crack propagation and stress wave transmission of 3 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Shock and Vibration 9

αn

N2-4

N2-3

N2-2

N2-1

N1-110 10 1020

N1-2 N1-3 N1-4

90deg

Dm

rb

Figure 12 Schematic diagram of monitoring point layout

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 13 P-T curve of different monitoring points of 1 simulation case (a) αn 0deg (b) αn 90deg

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

(b)

Figure 14 P-T curve of different monitoring points of 2 simulation case (a) αn 0deg (b) αn 90deg

10 Shock and Vibration

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 15 P-T curve of different monitoring points of 3 simulation case (a) αn 0deg (b) αn 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(b)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(c)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(d)

Figure 16 Effective stress curve of different monitoring points of 1 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 11

blasting the effective stress of each curve shows the sametrend if Dmrb is certain and the effective stress decreasesgradually and becomes stable with the increase of Dmrb For2 simulation case the peak value of effective stress de-creases with the increase of Dmrb and αn at is to say ifDmrb is certain the rock located at different directionsaround the blasthole suffered different effective stress thecloser the rock gets to the direction of water jet the biggerthe effective stress the rock suffered For 3 simulation casethe variation trend of effective stress is similar to that of 2simulation case but the peak value of each effective stresscurve is quite different By comparing each effective stresscurve of 2 simulation case and 3 simulation case we cansee that in the direction of water jet slot the peak value ofeffective stress of 3 simulation case is always bigger thanthat of 2 simulation case However in the direction per-pendicular to the direction of the jet slot the peak value ofeffective stress of 3 simulation case is always smaller than

that of 2 simulation case which indicates that the existenceof blasthole wall protection material is not only very ben-eficial to the ldquoguiding effectrdquo of blast-induced crack prop-agation by water jet slot but also beneficial to reduce blast-induced damage of remaining rock mass

Moreover by comparing Figures 16(d) 17(d) and 18(d)we can see that in the direction of water jet slot the effectivestress of 2 simulation case decreases gradually and whenDmrb is 20 the distribution-evolution law of effective stressis similar to that of 1 simulation case However for 3simulation case when Dmrb is 20 the peak value of effectivestress is bigger than that of 2 simulation case and thegrowing trend of effective stress shows a large fluctuationwhich suggested that the rock suffered the ldquoguiding effectrdquo bywater jet slot In addition in the other direction of blastholethe distribution-evolution law of effective stress is similar tothat of 1 simulation case at is to say the bigger Dmrb isthe weaker the ldquoguiding effectrdquo and ldquoblasthole wall

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 17 Effective stress curve of different monitoring points of 2 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

12 Shock and Vibration

protection effectrdquo by water jet slot and wall protectionmaterial are

4 Conclusions

In summary some conclusions can be summarized asfollows

e experiment test on dynamic blast strain was con-ducted and the results indicated that under the combinedeffect of blasthole wall protection material and water jet slotthe blasting strain fields were changed by comparing withthe regular blasthole blasting In the direction of water jetslot the PSPV was increased by 8500 and in the directionperpendicular to the direction of water jet slot the PSPV wasreduced by 7021

Numerical simulation results suggest that the existence ofwater jet slot and blasthole wall protection material can affectthe distribution and evolution law of explosive stress waveand let the stress concentration occur at the tip of water jet

slot which promotes blast-induced crack propagation alongthe specific direction and minimizes the blast-induceddamage of remaining rock mass Moreover the bigger Dmrb is the weaker the ldquoguiding effectrdquo and ldquoblasthole wallprotection effectrdquo by water jet slot and wall protection ma-terial are

Both the experiment test result and the numericalsimulation results indicated that the existence of blastholewall protection material is not only beneficial to the ldquoguidingeffectrdquo of blast-induced crack propagation of water jet slotbut also beneficial to reduce blast-induced damage ofremaining rock mass

Future research work will be focused on the applicationsin practical engineering of this approach

Data Availability

Readers can access the data supporting the conclusions ofthe study by sending a mail to the corresponding author

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 18 Effective stress curve of different monitoring points of 3 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 13

(e-mail dengfengcqu163com) and all data can be cosh-ared without restriction

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

Financial support for this work was provided by the NaturalScience Foundation of Southwest University of Science andTechnology (18zx7124) In particular the authors thank ME D Y Li and M E F W Yan for their kind help inexperimental investigation and sincere suggestion

References

[1] Z N Zhao X T Feng Y X Xiao et al ldquoMicroseismiccharacteristics and rockburst risk of deep tunnel constructedby different excavation methodsrdquo Chinese Journal of Geo-technical Engineering vol 38 no 5 pp 0867ndash0876 2016

[2] Z C Zhang ldquoControl in blasting engineeringrdquo ChineseJournal of Underground Space and Engineering vol 9 no 5pp 1208ndash1214 2013

[3] Y Wang ldquoStudy of the dynamic fracture effect using slottedcartridge decoupling charge blastingrdquo International Journal ofRock Mechanics and Mining Sciences vol 96 pp 34ndash46 2017

[4] S S Rathore and S Bhandari ldquoControlled fracture growth byblasting while protecting damages to remaining rockrdquo RockMechanics and Rock Engineering vol 40 no 3 pp 317ndash3262007

[5] S H Cho Y Nakamura B Mohanty H S Yang andK Kaneko ldquoNumerical study of fracture plane control inlaboratory-scale blastingrdquo Engineering Fracture Mechanicsvol 75 no 13 pp 3966ndash3984 2008

[6] R S Yang Y B Wang and L Y Yang ldquoDynamic causticexperimental study of crack propagation in two borehole cutblastingrdquo Journal of China University of Mining amp Technologyvol 41 no 6 pp 868ndash872 2012

[7] WM Liang X L Yang and Y Q Yu ldquoResearch on theory ondirectional fracture controlled blastingrdquo Journal of LiaoningTechnical University vol 25 no 5 pp 702ndash704 2006

[8] J S Song Y B Wang X T Gao et al ldquoe mechanism ofdirectional fracture controlled blasting and its applicationrdquoJournal of Mining Science and Technology vol 1 no 1pp 16ndash28 2016

[9] Y Wang ldquoExperimental research on the influence of anempty-hole defect on crack connections between a direc-tionally fractured blast holerdquo Journal of Testing and Evalu-ation vol 45 no 6 pp 2139ndash2150 2017

[10] Z Li W Chen and H Hao ldquoNumerical study of sandwichpanel with a new bi-directional load-self-cancelling (LSC)core under blast loadingrdquo =in-Walled Structures vol 127pp 90ndash101 2018

[11] K Katsuyama H Kiyokawa and K Sassa ldquoControl thegrowth of cracks from a borehole by a new method of smoothblastingrdquo Mining Safety vol 29 pp 16ndash23 1983

[12] W L Fourney D B Barker and D C Holloway ldquoModelstudies of explosive well stimulation techniquesrdquo In-ternational Journal of Rock Mechanics and Mining Sciences ampGeomechanics Abstracts vol 18 no 2 pp 113ndash127 1981

[13] W L Fourney D B Barker and D C Holloway ldquoModelstudies of well stimulation using propellant chargesrdquo

International Journal of Rock Mechanics and Mining Sciencesamp Geomechanics Abstracts vol 20 no 2 pp 91ndash101 1983

[14] B Mohanty ldquoExplosive generated fractures in rock and rocklike materialsrdquo Engineering Fracture Mechanics vol 35 no 4-5 pp 889ndash898 1990

[15] B Mohanty ldquoFracture-plane control blasts with satelliteholesrdquo in Proceedings of 3rd International Symposium on RockFragmentation by Blasting pp 407ndash418 Australasian Instituteof Mining and Metallurgy Parkville Australia August 1990

[16] Y G Du Z C Zhang and T L Li ldquoStudies on mechanicaleffect produced by the V-shaped notch borehole blastingrdquoExplosion and Shock Waves vol 11 pp 26ndash30 1991

[17] Q Zong ldquoeoretical study on the cracking mechanism ofnotched borehole blastingrdquo Coal Mine Blasting vol 1pp 12ndash16 1995

[18] Q Zong ldquoInvestigations into mechanism of crack formationfor grooved hole-well blastingrdquo Chinese Journal of Geo-technical Engineering vol 20 no 1 pp 30ndash33 1998

[19] S H Cho Y Nakamura and K Kaneko ldquoDynamic fractureprocess analysis of rock subjected to a stress wave and gaspressurizationrdquo International Journal of Rock Mechanics andMining Sciences vol 41 no 3 pp 433ndash440 2004

[20] Y Zhang ldquoDynamic numerical simulation for the mechanismof V-shaped notch blastingrdquo Explosive Materials vol 38no 4 pp 1ndash5 2009

[21] R S Yang and Y B Wang ldquoDynamic caustic experiment onfracture behaviors of flawed material induced by pre-notchedblastingrdquo Explosive and Shock Waves vol 36 no 2pp 145ndash152 2016

[22] R S Yang C X Ding L Y Yang P Xu and C Chen ldquoHoledefects affect the dynamic fracture behavior of nearby runningcracksrdquo Shock and Vibration vol 2018 Article ID 58943568 pages 2018

[23] Z W Yue Y Guo X Wang et al ldquoInfluence of empty holeshape on directional fracture controlled blasting of rockrdquoRock and Soil Mechanics vol 37 no 2 pp 376ndash382 2016

[24] Z Yue P Qiu R Yang S Zhang K Yuan and Z Li ldquoStressanalysis of the interaction of a running crack and blastingwaves by caustics methodrdquo Engineering Fracture Mechanicsvol 184 pp 339ndash351 2017

[25] B Chen C Liu and J X Yang ldquoAnalysis and application oncontrolling thick hard roof caving with deep-hole positionpresplitting blastingrdquoAdvances in Civil Engineering vol 2018Article ID 9763137 15 pages 2018

[26] Y H Zhu and X P Xu ldquoDamage control characteristics fornotched blasting based on the damage mechanismrdquo Journal ofChina Coal Society vol 42 no 2 pp 369ndash376 2017

[27] X H Li L Yang J S Wang et al ldquoe natural frequencycharacteristic of the self-excited oscillation pulsed water jetdevicerdquo Journal of China Coal Society vol 25 no 6pp 641ndash644 2000

[28] X H Li Y Y Lu Y Zhao et al ldquoStudy on improving thepermeability of soft coal seam with high pressure pulsed waterjetrdquo Journal of China Coal Society vol 33 no 12 pp 1386ndash1390 2007

[29] Y Kang X C Wang X F Yang et al ldquoNumerical simulationof control blasting with borehole protecting and water jetslotting in soft rock massrdquo Disaster Advances vol 5 no 4pp 933ndash938 2012

[30] J-G Kim and J-J Song ldquoAbrasive water jet cutting methodsfor reducing blast-induced ground vibration in tunnel ex-cavationrdquo International Journal of Rock Mechanics andMining Sciences vol 75 pp 147ndash158 2015

14 Shock and Vibration

[31] Y Kang D D Zheng D F Su et al ldquoModel of directionalshaped blasting assisted with water jet and its numericalsimulationrdquo Journal of Vibration and Shock vol 34pp 182ndash188 2015

[32] D Su Y Kang F Yan D Zheng X Wang and M WeildquoCrack propagation law affected by natural fracture and waterjet slot under blast loadingrdquo Combustion Explosion andShock Waves vol 54 no 6 pp 747ndash756 2018

[33] Y B Wang ldquoRock dynamic fracture characteristics based onNSCB impact methodrdquo Shock and Vibration vol 2018 Ar-ticle ID 3105384 13 pages 2018

[34] J Dai Dynamic Behaviors and Blasting =eory of RockMetallurgical Industry Press Beijing China 2013

[35] LSTC LS-DYNAKeyword Userrsquos Manual Livermore SoftwareTechnology Corporation Livermore CA USA 2007

Shock and Vibration 15

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Page 5: ExperimentalStudyandNumericalSimulationofDynamic Stress ...downloads.hindawi.com/journals/sv/2019/1659175.pdf,kLL jLL xLL L xLL jLL,kLL L L©L, L©Lk L©Lff L©Lx _NF ig E NFE #_#YNIkff©,Ifiig

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 636454μεNSPV ndash495945μεMSPV 83223με

(a)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 537698μεNSPV ndash248893μεMSPV 73074με

(b)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 672342μεNSPV ndash722151μεMSPV 92998με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 570690μεNSPV ndash396569μεMSPV 78041με

(d)

Figure 5 Waveform curve of dynamic strain for 1 test model (a) E1-1 test point (b) E1-2 test point (c) E1-3 test point and (d) E1-4test point

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 869829μεNSPV ndash341492μεMSPV 171153με

(a)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 633962μεNSPV ndash280124μεMSPV 132421με

(b)

Figure 6 Continued

Shock and Vibration 5

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 623167μεNSPV ndash718531μεMSPV 80121με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 520278μεNSPV ndash388996μεMSPV 63676με

(d)

Figure 6 Waveform curve of dynamic strain for 2 test model (a) E2-1 test point (b) E2-2 test point (c) E2-3 test point and (d) E2-4test point

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 1177456μεNSPV ndash772859μεMSPV 224876με

(a)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 810468μεNSPV ndash348843μεMSPV 189897με

(b)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 350768μεNSPV ndash368530μεMSPV 27480με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 295034μεNSPV ndash271644μεMSPV 12654με

(d)

Figure 7 Waveform curve of dynamic strain for 3 test model (a) E3-1 test point (b) E3-2 test point (c) E3-3 test point and (d) E3-4test point

6 Shock and Vibration

3 Numerical Simulation of BlastStress Evolution

e FEM software ANSYSLS-DYNA and the post-processing software LS-PREPOST were applied to in-vestigate the blasting stress wave evolution law and the blast-induced crack propagation law for different conditions

31 Numerical Simulation Model ree simulation caseswere conducted by ANSYSLS-DYNA Due to the symmetryof the simulated object both simulation cases applied aquasi-2D simulation model For each case the size of rock is150 cmtimes 150 cmtimes 03 cm the diameter of blasthole is 5 cmthe thickness of the blasthole wall protection material is05 cm and the size of the water jet slot is25 cmtimes 05 cmtimes 03 cm e 3 simulation model is shownin Figure 8

32 Material Model

321 Rock Material type 3 of LS-DYNA (lowastMAT_PLASTIC_KINEMATIC) was applied to model the rock [35] and itsparameters are shown in Table 3

322 BlastholeWall ProtectionMaterial Material type 3 ofLS-DYNA (lowastMAT_PLASTIC_KINEMATIC) was applied tomodel the blasthole wall protection material [35] and itsparameters are shown in Table 4

323 Explosive Material type 8 of LS-DYNA(lowastMAT_HIGH_EXPLOSIVE_BURN) was chosen as theexplosive model and the pressure released by the chemicalenergy in the engineering calculations was modelled by theJonesndashWilkinsndashLee equation of state e JWL EOS can bewritten in the following form [35]

Pe A 1minusω

R1V1113888 1113889e

minusR1V+ B 1minus

ωR2V

1113888 1113889eminusR2V

+ωEe

V (1)

where Pe is the pressure produced by the detonationproducts from explosive where ω A B R1 and R2 are user-defined input parameters V is the relative volume and Ee isthe internal energy per initial volume as shown in Table 5

324 Air Air was modelled by the material type 9 of LS-DYNA (lowastMAT_NULL) with the Gruneisen equation epressure Pa can be calculated by [35]

Pa C0 + C1μ + C2μ2 + C3μ3 + C4 + C5μ + C6μ2( 1113857Ea

μ 1

Vaminus 1

⎧⎪⎪⎪⎪⎨

⎪⎪⎪⎪⎩

(2)

where C0 C1 C2 C3 C4 C5 and C6 are user-definedconstants ρa is the density of air Va is the relative

volume of air Ea is the internal energy of air as shown inTable 6

33 Numerical Calculation Algorithm Lagrange algorithmhas the priority of less computation time and accuratelydescribing the boundary movement of structure so it isalways used to analyze the explosive detonation Howeverit has a big disadvantage of causing element distortion andeven leads to the termination of calculation when dealingwith the large deformation numerical calculation Inorder to avoid the above problem fluid-solid couplingalgorithm was adopted for the analysis of the explosivedetonation of which ALE algorithm was used for ex-plosive and air and Lagrange algorithm for rock andprotecting pipe e material derivative equation and thegoverning equations of the ALE algorithm can beexpressed as follows [35]

df(X t)

dt

zf(ξ t)

zt+ vi minuswi( 1113857

zf(x t)

zxi

zρzt

ρzυi

zx+ ωi

zρzx

ρzυi

zt+ ρωi

zυi

zxj

zσij

zxj

+ ρfi

ρze

zt σij

zυi

zxj

minuszq

zxj

minus ρωi

ze

zxi

(3)

where f is the physical quantity vi is the velocity of particleX ωi is the velocity of the computational grid xi is theLagrangian coordinate system yi is the Eulerian coordinatesystem ρ is the density v is the particle velocity e is theinternal energy of unit mass σij is the Cauchy stress tensorfi is the body force qi is the heat flux and subscripts i and j

stand for the direction of coordinateAt the same time meshes of explosive and the air were

joined with common nodes and so as to rock and protectingpipe en the fluid-solid coupling was defined between themeshes of the explosive air rock and protecting pipe by thekeyword In addition according to the characteristics ofblasting process the time step of the simulation is 067 andthe computation time is 0004 s

34 Simulation Results Analysis e Postprocessing soft-ware LS-PREPOST was used to draw the diagrams of theevolution law of explosion stress wave and crack propaga-tion of different simulation cases as shown in Figures 9ndash11

In general for regular blasthole blasting the explosionstress uniformly acts on the wall of blasthole and the shapeof blast stress wave is round and then the blast-inducedcrack forms and expands under the blast loading Due to thecharacters of blast loading the gas pressure acting onblasthole wall in all directions can be considered as equiv-alent so the well-distributed blast-induced cracks generatenear the blasthole which is consistent with the classicalblasting theory

Shock and Vibration 7

However by comparing 1 simulation case the blast-induced crack propagation law and the transmission law ofexplosion stress wave of 2 simulation case and 3 simu-lation case were greatly changed under the effect of water jetslot and blasthole wall protection materials On one handblasting energy focus forms at the initial stage of the ex-plosion which promotes the initial microcrack produced atthe direction of water jet slot And nothing but air is in thewater jet slot which caused the formation of low-pressurezone so detonation products have priority to flow along thedirection of water jet slot en the high-pressure and high-velocity gas products wedge into the slot further leading tocrack initiation and extension along the desired direction asshown in Figures 10 and 11 On the other hand as the failureof blasthole wall protectionmaterial makes a large amount ofconsumption of blast energy the formation of microcrack ofthe remaining rock mass was restrained Furthermorethe blasthole wall protection material is in a molten stateduring the blasting which will wedge into the unexpected

microcracks and then the ldquogas edge effectrdquo of gas productwill be greatly weakened So the dual purpose of directionalblast-induced crack propagation and remaining rock massprotection is realized

To further understand the transmission law of blaststress wave and the change regularity of blasting strain underdifferent conditions monitoring points were set in thenumerical simulation model and its schematic diagram isshown in Figure 12 where Dm stands for the distance be-tween the monitoring point and the center of blasthole rbstands for the radius of blasthole and αn is the angle betweentwo lines one is the connection between blasthole center andwater jet slot and the another is the connection betweenblasthole center and monitoring point

Figures 13ndash15 show the P-T curves of different simu-lation cases from which we can see that with the increase ofDm the pressure of different cases almost shows a trend ofgradual decrease but the pressure of different monitoringpoints of different cases shows a different changing trendFor 1 simulation case when Dmrb is certain each P-Tcurve shows the same trend because of the explosion at isbecause the explosion stress uniformly acts on the wall ofblasthole during blasting which is consistent with experi-ment test result For 2 simulation case when αn is 0deg the

Table 3 Parameters of rock

Density (gcm3) Elastic modulus (MPa) Tangent modulus (MPa) Poisson ratio Yield strength (MPa) SRC SRP Failure strain250 225times104 420times103 022 300 0 0 006

Table 4 Parameters of blasthole wall protection material

Density (gcm3) Elastic modulus (MPa) Poisson ratio Yield strength (MPa) SRC SRP Failure strain143 300times103 03 18times10minus1 0 0 01

Table 5 Parameters of explosive and its EOS equation

ρe (gcm3) vD (cmμs) Pcut (MPa) A (MPa) B (MPa) R1 R2 ω

170 083 295times104 855times105 205times104 460 135 025

Table 6 Parameters of air and its EOS equation

ρa (gcm3) C0 C1 C2 C3 C4 C5 C6

120times10minus3 000 000 000 000 040 040 000

Nonreflected boundaryRock

Nonreflected boundary

A

75

150

150

75

Blasthole wall protection material

Explosive

Water jet slot

(a) (b)

Figure 8 Numerical simulation model (a) 3 simulation model (b) enlargement of part A

8 Shock and Vibration

peak value of the measuring point is smaller than that ofregular blasting but the valley value is bigger than that ofregular blasthole blasting at is to say the rock will besubjected to tensile stress As we know the tensile strength ofrock is far less than its compressive strength so the rock isvulnerable to failure [34] which suggest that the existence ofthe water jet slot changed the distribution laws of stress fieldsduring blasting let the blast-induced crack initiation andpropagation in the direction of water jet slot

For 3 simulation case when αn is 0deg though the peakvalue continues to decline valley value is 4040 greaterthan that of 2 simulation case Moreover the action time of

tensile stress of 3 simulation case is much longer than thatof 2 simulation case When αn is 90deg the peak value is2534 and 2966 smaller than that of 2 simulation caseand 1 simulation case respectively which demonstratesthat the existence of blasthole wall protection material hascreated more favorable conditions for the blast-inducedcrack propagation along the direction of water jet slotand the protection of blasthole wall during blasting which isconsistent with the above analysis

Figures 16ndash18 present the effective stress curves of dif-ferent simulation cases For 1 simulation case as the ex-plosion stress uniformly acts on the wall of blasthole during

Blast stress wave Blast-induced crack

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 9 Diagram of blast-induced crack propagation and stress wave transmission of 1 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focus Blast-induced crack

Stress concentration

Blast stress wave

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 10 Diagram of blast-induced crack propagation and stress wave transmission of 2 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focusBlast-induced crack

Stress concentration

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 11 Diagram of blast-induced crack propagation and stress wave transmission of 3 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Shock and Vibration 9

αn

N2-4

N2-3

N2-2

N2-1

N1-110 10 1020

N1-2 N1-3 N1-4

90deg

Dm

rb

Figure 12 Schematic diagram of monitoring point layout

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 13 P-T curve of different monitoring points of 1 simulation case (a) αn 0deg (b) αn 90deg

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

(b)

Figure 14 P-T curve of different monitoring points of 2 simulation case (a) αn 0deg (b) αn 90deg

10 Shock and Vibration

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 15 P-T curve of different monitoring points of 3 simulation case (a) αn 0deg (b) αn 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(b)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(c)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(d)

Figure 16 Effective stress curve of different monitoring points of 1 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 11

blasting the effective stress of each curve shows the sametrend if Dmrb is certain and the effective stress decreasesgradually and becomes stable with the increase of Dmrb For2 simulation case the peak value of effective stress de-creases with the increase of Dmrb and αn at is to say ifDmrb is certain the rock located at different directionsaround the blasthole suffered different effective stress thecloser the rock gets to the direction of water jet the biggerthe effective stress the rock suffered For 3 simulation casethe variation trend of effective stress is similar to that of 2simulation case but the peak value of each effective stresscurve is quite different By comparing each effective stresscurve of 2 simulation case and 3 simulation case we cansee that in the direction of water jet slot the peak value ofeffective stress of 3 simulation case is always bigger thanthat of 2 simulation case However in the direction per-pendicular to the direction of the jet slot the peak value ofeffective stress of 3 simulation case is always smaller than

that of 2 simulation case which indicates that the existenceof blasthole wall protection material is not only very ben-eficial to the ldquoguiding effectrdquo of blast-induced crack prop-agation by water jet slot but also beneficial to reduce blast-induced damage of remaining rock mass

Moreover by comparing Figures 16(d) 17(d) and 18(d)we can see that in the direction of water jet slot the effectivestress of 2 simulation case decreases gradually and whenDmrb is 20 the distribution-evolution law of effective stressis similar to that of 1 simulation case However for 3simulation case when Dmrb is 20 the peak value of effectivestress is bigger than that of 2 simulation case and thegrowing trend of effective stress shows a large fluctuationwhich suggested that the rock suffered the ldquoguiding effectrdquo bywater jet slot In addition in the other direction of blastholethe distribution-evolution law of effective stress is similar tothat of 1 simulation case at is to say the bigger Dmrb isthe weaker the ldquoguiding effectrdquo and ldquoblasthole wall

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 17 Effective stress curve of different monitoring points of 2 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

12 Shock and Vibration

protection effectrdquo by water jet slot and wall protectionmaterial are

4 Conclusions

In summary some conclusions can be summarized asfollows

e experiment test on dynamic blast strain was con-ducted and the results indicated that under the combinedeffect of blasthole wall protection material and water jet slotthe blasting strain fields were changed by comparing withthe regular blasthole blasting In the direction of water jetslot the PSPV was increased by 8500 and in the directionperpendicular to the direction of water jet slot the PSPV wasreduced by 7021

Numerical simulation results suggest that the existence ofwater jet slot and blasthole wall protection material can affectthe distribution and evolution law of explosive stress waveand let the stress concentration occur at the tip of water jet

slot which promotes blast-induced crack propagation alongthe specific direction and minimizes the blast-induceddamage of remaining rock mass Moreover the bigger Dmrb is the weaker the ldquoguiding effectrdquo and ldquoblasthole wallprotection effectrdquo by water jet slot and wall protection ma-terial are

Both the experiment test result and the numericalsimulation results indicated that the existence of blastholewall protection material is not only beneficial to the ldquoguidingeffectrdquo of blast-induced crack propagation of water jet slotbut also beneficial to reduce blast-induced damage ofremaining rock mass

Future research work will be focused on the applicationsin practical engineering of this approach

Data Availability

Readers can access the data supporting the conclusions ofthe study by sending a mail to the corresponding author

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 18 Effective stress curve of different monitoring points of 3 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 13

(e-mail dengfengcqu163com) and all data can be cosh-ared without restriction

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

Financial support for this work was provided by the NaturalScience Foundation of Southwest University of Science andTechnology (18zx7124) In particular the authors thank ME D Y Li and M E F W Yan for their kind help inexperimental investigation and sincere suggestion

References

[1] Z N Zhao X T Feng Y X Xiao et al ldquoMicroseismiccharacteristics and rockburst risk of deep tunnel constructedby different excavation methodsrdquo Chinese Journal of Geo-technical Engineering vol 38 no 5 pp 0867ndash0876 2016

[2] Z C Zhang ldquoControl in blasting engineeringrdquo ChineseJournal of Underground Space and Engineering vol 9 no 5pp 1208ndash1214 2013

[3] Y Wang ldquoStudy of the dynamic fracture effect using slottedcartridge decoupling charge blastingrdquo International Journal ofRock Mechanics and Mining Sciences vol 96 pp 34ndash46 2017

[4] S S Rathore and S Bhandari ldquoControlled fracture growth byblasting while protecting damages to remaining rockrdquo RockMechanics and Rock Engineering vol 40 no 3 pp 317ndash3262007

[5] S H Cho Y Nakamura B Mohanty H S Yang andK Kaneko ldquoNumerical study of fracture plane control inlaboratory-scale blastingrdquo Engineering Fracture Mechanicsvol 75 no 13 pp 3966ndash3984 2008

[6] R S Yang Y B Wang and L Y Yang ldquoDynamic causticexperimental study of crack propagation in two borehole cutblastingrdquo Journal of China University of Mining amp Technologyvol 41 no 6 pp 868ndash872 2012

[7] WM Liang X L Yang and Y Q Yu ldquoResearch on theory ondirectional fracture controlled blastingrdquo Journal of LiaoningTechnical University vol 25 no 5 pp 702ndash704 2006

[8] J S Song Y B Wang X T Gao et al ldquoe mechanism ofdirectional fracture controlled blasting and its applicationrdquoJournal of Mining Science and Technology vol 1 no 1pp 16ndash28 2016

[9] Y Wang ldquoExperimental research on the influence of anempty-hole defect on crack connections between a direc-tionally fractured blast holerdquo Journal of Testing and Evalu-ation vol 45 no 6 pp 2139ndash2150 2017

[10] Z Li W Chen and H Hao ldquoNumerical study of sandwichpanel with a new bi-directional load-self-cancelling (LSC)core under blast loadingrdquo =in-Walled Structures vol 127pp 90ndash101 2018

[11] K Katsuyama H Kiyokawa and K Sassa ldquoControl thegrowth of cracks from a borehole by a new method of smoothblastingrdquo Mining Safety vol 29 pp 16ndash23 1983

[12] W L Fourney D B Barker and D C Holloway ldquoModelstudies of explosive well stimulation techniquesrdquo In-ternational Journal of Rock Mechanics and Mining Sciences ampGeomechanics Abstracts vol 18 no 2 pp 113ndash127 1981

[13] W L Fourney D B Barker and D C Holloway ldquoModelstudies of well stimulation using propellant chargesrdquo

International Journal of Rock Mechanics and Mining Sciencesamp Geomechanics Abstracts vol 20 no 2 pp 91ndash101 1983

[14] B Mohanty ldquoExplosive generated fractures in rock and rocklike materialsrdquo Engineering Fracture Mechanics vol 35 no 4-5 pp 889ndash898 1990

[15] B Mohanty ldquoFracture-plane control blasts with satelliteholesrdquo in Proceedings of 3rd International Symposium on RockFragmentation by Blasting pp 407ndash418 Australasian Instituteof Mining and Metallurgy Parkville Australia August 1990

[16] Y G Du Z C Zhang and T L Li ldquoStudies on mechanicaleffect produced by the V-shaped notch borehole blastingrdquoExplosion and Shock Waves vol 11 pp 26ndash30 1991

[17] Q Zong ldquoeoretical study on the cracking mechanism ofnotched borehole blastingrdquo Coal Mine Blasting vol 1pp 12ndash16 1995

[18] Q Zong ldquoInvestigations into mechanism of crack formationfor grooved hole-well blastingrdquo Chinese Journal of Geo-technical Engineering vol 20 no 1 pp 30ndash33 1998

[19] S H Cho Y Nakamura and K Kaneko ldquoDynamic fractureprocess analysis of rock subjected to a stress wave and gaspressurizationrdquo International Journal of Rock Mechanics andMining Sciences vol 41 no 3 pp 433ndash440 2004

[20] Y Zhang ldquoDynamic numerical simulation for the mechanismof V-shaped notch blastingrdquo Explosive Materials vol 38no 4 pp 1ndash5 2009

[21] R S Yang and Y B Wang ldquoDynamic caustic experiment onfracture behaviors of flawed material induced by pre-notchedblastingrdquo Explosive and Shock Waves vol 36 no 2pp 145ndash152 2016

[22] R S Yang C X Ding L Y Yang P Xu and C Chen ldquoHoledefects affect the dynamic fracture behavior of nearby runningcracksrdquo Shock and Vibration vol 2018 Article ID 58943568 pages 2018

[23] Z W Yue Y Guo X Wang et al ldquoInfluence of empty holeshape on directional fracture controlled blasting of rockrdquoRock and Soil Mechanics vol 37 no 2 pp 376ndash382 2016

[24] Z Yue P Qiu R Yang S Zhang K Yuan and Z Li ldquoStressanalysis of the interaction of a running crack and blastingwaves by caustics methodrdquo Engineering Fracture Mechanicsvol 184 pp 339ndash351 2017

[25] B Chen C Liu and J X Yang ldquoAnalysis and application oncontrolling thick hard roof caving with deep-hole positionpresplitting blastingrdquoAdvances in Civil Engineering vol 2018Article ID 9763137 15 pages 2018

[26] Y H Zhu and X P Xu ldquoDamage control characteristics fornotched blasting based on the damage mechanismrdquo Journal ofChina Coal Society vol 42 no 2 pp 369ndash376 2017

[27] X H Li L Yang J S Wang et al ldquoe natural frequencycharacteristic of the self-excited oscillation pulsed water jetdevicerdquo Journal of China Coal Society vol 25 no 6pp 641ndash644 2000

[28] X H Li Y Y Lu Y Zhao et al ldquoStudy on improving thepermeability of soft coal seam with high pressure pulsed waterjetrdquo Journal of China Coal Society vol 33 no 12 pp 1386ndash1390 2007

[29] Y Kang X C Wang X F Yang et al ldquoNumerical simulationof control blasting with borehole protecting and water jetslotting in soft rock massrdquo Disaster Advances vol 5 no 4pp 933ndash938 2012

[30] J-G Kim and J-J Song ldquoAbrasive water jet cutting methodsfor reducing blast-induced ground vibration in tunnel ex-cavationrdquo International Journal of Rock Mechanics andMining Sciences vol 75 pp 147ndash158 2015

14 Shock and Vibration

[31] Y Kang D D Zheng D F Su et al ldquoModel of directionalshaped blasting assisted with water jet and its numericalsimulationrdquo Journal of Vibration and Shock vol 34pp 182ndash188 2015

[32] D Su Y Kang F Yan D Zheng X Wang and M WeildquoCrack propagation law affected by natural fracture and waterjet slot under blast loadingrdquo Combustion Explosion andShock Waves vol 54 no 6 pp 747ndash756 2018

[33] Y B Wang ldquoRock dynamic fracture characteristics based onNSCB impact methodrdquo Shock and Vibration vol 2018 Ar-ticle ID 3105384 13 pages 2018

[34] J Dai Dynamic Behaviors and Blasting =eory of RockMetallurgical Industry Press Beijing China 2013

[35] LSTC LS-DYNAKeyword Userrsquos Manual Livermore SoftwareTechnology Corporation Livermore CA USA 2007

Shock and Vibration 15

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Page 6: ExperimentalStudyandNumericalSimulationofDynamic Stress ...downloads.hindawi.com/journals/sv/2019/1659175.pdf,kLL jLL xLL L xLL jLL,kLL L L©L, L©Lk L©Lff L©Lx _NF ig E NFE #_#YNIkff©,Ifiig

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 623167μεNSPV ndash718531μεMSPV 80121με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 520278μεNSPV ndash388996μεMSPV 63676με

(d)

Figure 6 Waveform curve of dynamic strain for 2 test model (a) E2-1 test point (b) E2-2 test point (c) E2-3 test point and (d) E2-4test point

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 1177456μεNSPV ndash772859μεMSPV 224876με

(a)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 810468μεNSPV ndash348843μεMSPV 189897με

(b)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 350768μεNSPV ndash368530μεMSPV 27480με

(c)

ndash1200

ndash800

ndash400

0

400

800

1200

0 001 002 003 004

Stra

in (μ

ε)

Time (s)

PSPV 295034μεNSPV ndash271644μεMSPV 12654με

(d)

Figure 7 Waveform curve of dynamic strain for 3 test model (a) E3-1 test point (b) E3-2 test point (c) E3-3 test point and (d) E3-4test point

6 Shock and Vibration

3 Numerical Simulation of BlastStress Evolution

e FEM software ANSYSLS-DYNA and the post-processing software LS-PREPOST were applied to in-vestigate the blasting stress wave evolution law and the blast-induced crack propagation law for different conditions

31 Numerical Simulation Model ree simulation caseswere conducted by ANSYSLS-DYNA Due to the symmetryof the simulated object both simulation cases applied aquasi-2D simulation model For each case the size of rock is150 cmtimes 150 cmtimes 03 cm the diameter of blasthole is 5 cmthe thickness of the blasthole wall protection material is05 cm and the size of the water jet slot is25 cmtimes 05 cmtimes 03 cm e 3 simulation model is shownin Figure 8

32 Material Model

321 Rock Material type 3 of LS-DYNA (lowastMAT_PLASTIC_KINEMATIC) was applied to model the rock [35] and itsparameters are shown in Table 3

322 BlastholeWall ProtectionMaterial Material type 3 ofLS-DYNA (lowastMAT_PLASTIC_KINEMATIC) was applied tomodel the blasthole wall protection material [35] and itsparameters are shown in Table 4

323 Explosive Material type 8 of LS-DYNA(lowastMAT_HIGH_EXPLOSIVE_BURN) was chosen as theexplosive model and the pressure released by the chemicalenergy in the engineering calculations was modelled by theJonesndashWilkinsndashLee equation of state e JWL EOS can bewritten in the following form [35]

Pe A 1minusω

R1V1113888 1113889e

minusR1V+ B 1minus

ωR2V

1113888 1113889eminusR2V

+ωEe

V (1)

where Pe is the pressure produced by the detonationproducts from explosive where ω A B R1 and R2 are user-defined input parameters V is the relative volume and Ee isthe internal energy per initial volume as shown in Table 5

324 Air Air was modelled by the material type 9 of LS-DYNA (lowastMAT_NULL) with the Gruneisen equation epressure Pa can be calculated by [35]

Pa C0 + C1μ + C2μ2 + C3μ3 + C4 + C5μ + C6μ2( 1113857Ea

μ 1

Vaminus 1

⎧⎪⎪⎪⎪⎨

⎪⎪⎪⎪⎩

(2)

where C0 C1 C2 C3 C4 C5 and C6 are user-definedconstants ρa is the density of air Va is the relative

volume of air Ea is the internal energy of air as shown inTable 6

33 Numerical Calculation Algorithm Lagrange algorithmhas the priority of less computation time and accuratelydescribing the boundary movement of structure so it isalways used to analyze the explosive detonation Howeverit has a big disadvantage of causing element distortion andeven leads to the termination of calculation when dealingwith the large deformation numerical calculation Inorder to avoid the above problem fluid-solid couplingalgorithm was adopted for the analysis of the explosivedetonation of which ALE algorithm was used for ex-plosive and air and Lagrange algorithm for rock andprotecting pipe e material derivative equation and thegoverning equations of the ALE algorithm can beexpressed as follows [35]

df(X t)

dt

zf(ξ t)

zt+ vi minuswi( 1113857

zf(x t)

zxi

zρzt

ρzυi

zx+ ωi

zρzx

ρzυi

zt+ ρωi

zυi

zxj

zσij

zxj

+ ρfi

ρze

zt σij

zυi

zxj

minuszq

zxj

minus ρωi

ze

zxi

(3)

where f is the physical quantity vi is the velocity of particleX ωi is the velocity of the computational grid xi is theLagrangian coordinate system yi is the Eulerian coordinatesystem ρ is the density v is the particle velocity e is theinternal energy of unit mass σij is the Cauchy stress tensorfi is the body force qi is the heat flux and subscripts i and j

stand for the direction of coordinateAt the same time meshes of explosive and the air were

joined with common nodes and so as to rock and protectingpipe en the fluid-solid coupling was defined between themeshes of the explosive air rock and protecting pipe by thekeyword In addition according to the characteristics ofblasting process the time step of the simulation is 067 andthe computation time is 0004 s

34 Simulation Results Analysis e Postprocessing soft-ware LS-PREPOST was used to draw the diagrams of theevolution law of explosion stress wave and crack propaga-tion of different simulation cases as shown in Figures 9ndash11

In general for regular blasthole blasting the explosionstress uniformly acts on the wall of blasthole and the shapeof blast stress wave is round and then the blast-inducedcrack forms and expands under the blast loading Due to thecharacters of blast loading the gas pressure acting onblasthole wall in all directions can be considered as equiv-alent so the well-distributed blast-induced cracks generatenear the blasthole which is consistent with the classicalblasting theory

Shock and Vibration 7

However by comparing 1 simulation case the blast-induced crack propagation law and the transmission law ofexplosion stress wave of 2 simulation case and 3 simu-lation case were greatly changed under the effect of water jetslot and blasthole wall protection materials On one handblasting energy focus forms at the initial stage of the ex-plosion which promotes the initial microcrack produced atthe direction of water jet slot And nothing but air is in thewater jet slot which caused the formation of low-pressurezone so detonation products have priority to flow along thedirection of water jet slot en the high-pressure and high-velocity gas products wedge into the slot further leading tocrack initiation and extension along the desired direction asshown in Figures 10 and 11 On the other hand as the failureof blasthole wall protectionmaterial makes a large amount ofconsumption of blast energy the formation of microcrack ofthe remaining rock mass was restrained Furthermorethe blasthole wall protection material is in a molten stateduring the blasting which will wedge into the unexpected

microcracks and then the ldquogas edge effectrdquo of gas productwill be greatly weakened So the dual purpose of directionalblast-induced crack propagation and remaining rock massprotection is realized

To further understand the transmission law of blaststress wave and the change regularity of blasting strain underdifferent conditions monitoring points were set in thenumerical simulation model and its schematic diagram isshown in Figure 12 where Dm stands for the distance be-tween the monitoring point and the center of blasthole rbstands for the radius of blasthole and αn is the angle betweentwo lines one is the connection between blasthole center andwater jet slot and the another is the connection betweenblasthole center and monitoring point

Figures 13ndash15 show the P-T curves of different simu-lation cases from which we can see that with the increase ofDm the pressure of different cases almost shows a trend ofgradual decrease but the pressure of different monitoringpoints of different cases shows a different changing trendFor 1 simulation case when Dmrb is certain each P-Tcurve shows the same trend because of the explosion at isbecause the explosion stress uniformly acts on the wall ofblasthole during blasting which is consistent with experi-ment test result For 2 simulation case when αn is 0deg the

Table 3 Parameters of rock

Density (gcm3) Elastic modulus (MPa) Tangent modulus (MPa) Poisson ratio Yield strength (MPa) SRC SRP Failure strain250 225times104 420times103 022 300 0 0 006

Table 4 Parameters of blasthole wall protection material

Density (gcm3) Elastic modulus (MPa) Poisson ratio Yield strength (MPa) SRC SRP Failure strain143 300times103 03 18times10minus1 0 0 01

Table 5 Parameters of explosive and its EOS equation

ρe (gcm3) vD (cmμs) Pcut (MPa) A (MPa) B (MPa) R1 R2 ω

170 083 295times104 855times105 205times104 460 135 025

Table 6 Parameters of air and its EOS equation

ρa (gcm3) C0 C1 C2 C3 C4 C5 C6

120times10minus3 000 000 000 000 040 040 000

Nonreflected boundaryRock

Nonreflected boundary

A

75

150

150

75

Blasthole wall protection material

Explosive

Water jet slot

(a) (b)

Figure 8 Numerical simulation model (a) 3 simulation model (b) enlargement of part A

8 Shock and Vibration

peak value of the measuring point is smaller than that ofregular blasting but the valley value is bigger than that ofregular blasthole blasting at is to say the rock will besubjected to tensile stress As we know the tensile strength ofrock is far less than its compressive strength so the rock isvulnerable to failure [34] which suggest that the existence ofthe water jet slot changed the distribution laws of stress fieldsduring blasting let the blast-induced crack initiation andpropagation in the direction of water jet slot

For 3 simulation case when αn is 0deg though the peakvalue continues to decline valley value is 4040 greaterthan that of 2 simulation case Moreover the action time of

tensile stress of 3 simulation case is much longer than thatof 2 simulation case When αn is 90deg the peak value is2534 and 2966 smaller than that of 2 simulation caseand 1 simulation case respectively which demonstratesthat the existence of blasthole wall protection material hascreated more favorable conditions for the blast-inducedcrack propagation along the direction of water jet slotand the protection of blasthole wall during blasting which isconsistent with the above analysis

Figures 16ndash18 present the effective stress curves of dif-ferent simulation cases For 1 simulation case as the ex-plosion stress uniformly acts on the wall of blasthole during

Blast stress wave Blast-induced crack

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 9 Diagram of blast-induced crack propagation and stress wave transmission of 1 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focus Blast-induced crack

Stress concentration

Blast stress wave

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 10 Diagram of blast-induced crack propagation and stress wave transmission of 2 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focusBlast-induced crack

Stress concentration

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 11 Diagram of blast-induced crack propagation and stress wave transmission of 3 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Shock and Vibration 9

αn

N2-4

N2-3

N2-2

N2-1

N1-110 10 1020

N1-2 N1-3 N1-4

90deg

Dm

rb

Figure 12 Schematic diagram of monitoring point layout

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 13 P-T curve of different monitoring points of 1 simulation case (a) αn 0deg (b) αn 90deg

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

(b)

Figure 14 P-T curve of different monitoring points of 2 simulation case (a) αn 0deg (b) αn 90deg

10 Shock and Vibration

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 15 P-T curve of different monitoring points of 3 simulation case (a) αn 0deg (b) αn 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(b)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(c)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(d)

Figure 16 Effective stress curve of different monitoring points of 1 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 11

blasting the effective stress of each curve shows the sametrend if Dmrb is certain and the effective stress decreasesgradually and becomes stable with the increase of Dmrb For2 simulation case the peak value of effective stress de-creases with the increase of Dmrb and αn at is to say ifDmrb is certain the rock located at different directionsaround the blasthole suffered different effective stress thecloser the rock gets to the direction of water jet the biggerthe effective stress the rock suffered For 3 simulation casethe variation trend of effective stress is similar to that of 2simulation case but the peak value of each effective stresscurve is quite different By comparing each effective stresscurve of 2 simulation case and 3 simulation case we cansee that in the direction of water jet slot the peak value ofeffective stress of 3 simulation case is always bigger thanthat of 2 simulation case However in the direction per-pendicular to the direction of the jet slot the peak value ofeffective stress of 3 simulation case is always smaller than

that of 2 simulation case which indicates that the existenceof blasthole wall protection material is not only very ben-eficial to the ldquoguiding effectrdquo of blast-induced crack prop-agation by water jet slot but also beneficial to reduce blast-induced damage of remaining rock mass

Moreover by comparing Figures 16(d) 17(d) and 18(d)we can see that in the direction of water jet slot the effectivestress of 2 simulation case decreases gradually and whenDmrb is 20 the distribution-evolution law of effective stressis similar to that of 1 simulation case However for 3simulation case when Dmrb is 20 the peak value of effectivestress is bigger than that of 2 simulation case and thegrowing trend of effective stress shows a large fluctuationwhich suggested that the rock suffered the ldquoguiding effectrdquo bywater jet slot In addition in the other direction of blastholethe distribution-evolution law of effective stress is similar tothat of 1 simulation case at is to say the bigger Dmrb isthe weaker the ldquoguiding effectrdquo and ldquoblasthole wall

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 17 Effective stress curve of different monitoring points of 2 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

12 Shock and Vibration

protection effectrdquo by water jet slot and wall protectionmaterial are

4 Conclusions

In summary some conclusions can be summarized asfollows

e experiment test on dynamic blast strain was con-ducted and the results indicated that under the combinedeffect of blasthole wall protection material and water jet slotthe blasting strain fields were changed by comparing withthe regular blasthole blasting In the direction of water jetslot the PSPV was increased by 8500 and in the directionperpendicular to the direction of water jet slot the PSPV wasreduced by 7021

Numerical simulation results suggest that the existence ofwater jet slot and blasthole wall protection material can affectthe distribution and evolution law of explosive stress waveand let the stress concentration occur at the tip of water jet

slot which promotes blast-induced crack propagation alongthe specific direction and minimizes the blast-induceddamage of remaining rock mass Moreover the bigger Dmrb is the weaker the ldquoguiding effectrdquo and ldquoblasthole wallprotection effectrdquo by water jet slot and wall protection ma-terial are

Both the experiment test result and the numericalsimulation results indicated that the existence of blastholewall protection material is not only beneficial to the ldquoguidingeffectrdquo of blast-induced crack propagation of water jet slotbut also beneficial to reduce blast-induced damage ofremaining rock mass

Future research work will be focused on the applicationsin practical engineering of this approach

Data Availability

Readers can access the data supporting the conclusions ofthe study by sending a mail to the corresponding author

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 18 Effective stress curve of different monitoring points of 3 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 13

(e-mail dengfengcqu163com) and all data can be cosh-ared without restriction

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

Financial support for this work was provided by the NaturalScience Foundation of Southwest University of Science andTechnology (18zx7124) In particular the authors thank ME D Y Li and M E F W Yan for their kind help inexperimental investigation and sincere suggestion

References

[1] Z N Zhao X T Feng Y X Xiao et al ldquoMicroseismiccharacteristics and rockburst risk of deep tunnel constructedby different excavation methodsrdquo Chinese Journal of Geo-technical Engineering vol 38 no 5 pp 0867ndash0876 2016

[2] Z C Zhang ldquoControl in blasting engineeringrdquo ChineseJournal of Underground Space and Engineering vol 9 no 5pp 1208ndash1214 2013

[3] Y Wang ldquoStudy of the dynamic fracture effect using slottedcartridge decoupling charge blastingrdquo International Journal ofRock Mechanics and Mining Sciences vol 96 pp 34ndash46 2017

[4] S S Rathore and S Bhandari ldquoControlled fracture growth byblasting while protecting damages to remaining rockrdquo RockMechanics and Rock Engineering vol 40 no 3 pp 317ndash3262007

[5] S H Cho Y Nakamura B Mohanty H S Yang andK Kaneko ldquoNumerical study of fracture plane control inlaboratory-scale blastingrdquo Engineering Fracture Mechanicsvol 75 no 13 pp 3966ndash3984 2008

[6] R S Yang Y B Wang and L Y Yang ldquoDynamic causticexperimental study of crack propagation in two borehole cutblastingrdquo Journal of China University of Mining amp Technologyvol 41 no 6 pp 868ndash872 2012

[7] WM Liang X L Yang and Y Q Yu ldquoResearch on theory ondirectional fracture controlled blastingrdquo Journal of LiaoningTechnical University vol 25 no 5 pp 702ndash704 2006

[8] J S Song Y B Wang X T Gao et al ldquoe mechanism ofdirectional fracture controlled blasting and its applicationrdquoJournal of Mining Science and Technology vol 1 no 1pp 16ndash28 2016

[9] Y Wang ldquoExperimental research on the influence of anempty-hole defect on crack connections between a direc-tionally fractured blast holerdquo Journal of Testing and Evalu-ation vol 45 no 6 pp 2139ndash2150 2017

[10] Z Li W Chen and H Hao ldquoNumerical study of sandwichpanel with a new bi-directional load-self-cancelling (LSC)core under blast loadingrdquo =in-Walled Structures vol 127pp 90ndash101 2018

[11] K Katsuyama H Kiyokawa and K Sassa ldquoControl thegrowth of cracks from a borehole by a new method of smoothblastingrdquo Mining Safety vol 29 pp 16ndash23 1983

[12] W L Fourney D B Barker and D C Holloway ldquoModelstudies of explosive well stimulation techniquesrdquo In-ternational Journal of Rock Mechanics and Mining Sciences ampGeomechanics Abstracts vol 18 no 2 pp 113ndash127 1981

[13] W L Fourney D B Barker and D C Holloway ldquoModelstudies of well stimulation using propellant chargesrdquo

International Journal of Rock Mechanics and Mining Sciencesamp Geomechanics Abstracts vol 20 no 2 pp 91ndash101 1983

[14] B Mohanty ldquoExplosive generated fractures in rock and rocklike materialsrdquo Engineering Fracture Mechanics vol 35 no 4-5 pp 889ndash898 1990

[15] B Mohanty ldquoFracture-plane control blasts with satelliteholesrdquo in Proceedings of 3rd International Symposium on RockFragmentation by Blasting pp 407ndash418 Australasian Instituteof Mining and Metallurgy Parkville Australia August 1990

[16] Y G Du Z C Zhang and T L Li ldquoStudies on mechanicaleffect produced by the V-shaped notch borehole blastingrdquoExplosion and Shock Waves vol 11 pp 26ndash30 1991

[17] Q Zong ldquoeoretical study on the cracking mechanism ofnotched borehole blastingrdquo Coal Mine Blasting vol 1pp 12ndash16 1995

[18] Q Zong ldquoInvestigations into mechanism of crack formationfor grooved hole-well blastingrdquo Chinese Journal of Geo-technical Engineering vol 20 no 1 pp 30ndash33 1998

[19] S H Cho Y Nakamura and K Kaneko ldquoDynamic fractureprocess analysis of rock subjected to a stress wave and gaspressurizationrdquo International Journal of Rock Mechanics andMining Sciences vol 41 no 3 pp 433ndash440 2004

[20] Y Zhang ldquoDynamic numerical simulation for the mechanismof V-shaped notch blastingrdquo Explosive Materials vol 38no 4 pp 1ndash5 2009

[21] R S Yang and Y B Wang ldquoDynamic caustic experiment onfracture behaviors of flawed material induced by pre-notchedblastingrdquo Explosive and Shock Waves vol 36 no 2pp 145ndash152 2016

[22] R S Yang C X Ding L Y Yang P Xu and C Chen ldquoHoledefects affect the dynamic fracture behavior of nearby runningcracksrdquo Shock and Vibration vol 2018 Article ID 58943568 pages 2018

[23] Z W Yue Y Guo X Wang et al ldquoInfluence of empty holeshape on directional fracture controlled blasting of rockrdquoRock and Soil Mechanics vol 37 no 2 pp 376ndash382 2016

[24] Z Yue P Qiu R Yang S Zhang K Yuan and Z Li ldquoStressanalysis of the interaction of a running crack and blastingwaves by caustics methodrdquo Engineering Fracture Mechanicsvol 184 pp 339ndash351 2017

[25] B Chen C Liu and J X Yang ldquoAnalysis and application oncontrolling thick hard roof caving with deep-hole positionpresplitting blastingrdquoAdvances in Civil Engineering vol 2018Article ID 9763137 15 pages 2018

[26] Y H Zhu and X P Xu ldquoDamage control characteristics fornotched blasting based on the damage mechanismrdquo Journal ofChina Coal Society vol 42 no 2 pp 369ndash376 2017

[27] X H Li L Yang J S Wang et al ldquoe natural frequencycharacteristic of the self-excited oscillation pulsed water jetdevicerdquo Journal of China Coal Society vol 25 no 6pp 641ndash644 2000

[28] X H Li Y Y Lu Y Zhao et al ldquoStudy on improving thepermeability of soft coal seam with high pressure pulsed waterjetrdquo Journal of China Coal Society vol 33 no 12 pp 1386ndash1390 2007

[29] Y Kang X C Wang X F Yang et al ldquoNumerical simulationof control blasting with borehole protecting and water jetslotting in soft rock massrdquo Disaster Advances vol 5 no 4pp 933ndash938 2012

[30] J-G Kim and J-J Song ldquoAbrasive water jet cutting methodsfor reducing blast-induced ground vibration in tunnel ex-cavationrdquo International Journal of Rock Mechanics andMining Sciences vol 75 pp 147ndash158 2015

14 Shock and Vibration

[31] Y Kang D D Zheng D F Su et al ldquoModel of directionalshaped blasting assisted with water jet and its numericalsimulationrdquo Journal of Vibration and Shock vol 34pp 182ndash188 2015

[32] D Su Y Kang F Yan D Zheng X Wang and M WeildquoCrack propagation law affected by natural fracture and waterjet slot under blast loadingrdquo Combustion Explosion andShock Waves vol 54 no 6 pp 747ndash756 2018

[33] Y B Wang ldquoRock dynamic fracture characteristics based onNSCB impact methodrdquo Shock and Vibration vol 2018 Ar-ticle ID 3105384 13 pages 2018

[34] J Dai Dynamic Behaviors and Blasting =eory of RockMetallurgical Industry Press Beijing China 2013

[35] LSTC LS-DYNAKeyword Userrsquos Manual Livermore SoftwareTechnology Corporation Livermore CA USA 2007

Shock and Vibration 15

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Page 7: ExperimentalStudyandNumericalSimulationofDynamic Stress ...downloads.hindawi.com/journals/sv/2019/1659175.pdf,kLL jLL xLL L xLL jLL,kLL L L©L, L©Lk L©Lff L©Lx _NF ig E NFE #_#YNIkff©,Ifiig

3 Numerical Simulation of BlastStress Evolution

e FEM software ANSYSLS-DYNA and the post-processing software LS-PREPOST were applied to in-vestigate the blasting stress wave evolution law and the blast-induced crack propagation law for different conditions

31 Numerical Simulation Model ree simulation caseswere conducted by ANSYSLS-DYNA Due to the symmetryof the simulated object both simulation cases applied aquasi-2D simulation model For each case the size of rock is150 cmtimes 150 cmtimes 03 cm the diameter of blasthole is 5 cmthe thickness of the blasthole wall protection material is05 cm and the size of the water jet slot is25 cmtimes 05 cmtimes 03 cm e 3 simulation model is shownin Figure 8

32 Material Model

321 Rock Material type 3 of LS-DYNA (lowastMAT_PLASTIC_KINEMATIC) was applied to model the rock [35] and itsparameters are shown in Table 3

322 BlastholeWall ProtectionMaterial Material type 3 ofLS-DYNA (lowastMAT_PLASTIC_KINEMATIC) was applied tomodel the blasthole wall protection material [35] and itsparameters are shown in Table 4

323 Explosive Material type 8 of LS-DYNA(lowastMAT_HIGH_EXPLOSIVE_BURN) was chosen as theexplosive model and the pressure released by the chemicalenergy in the engineering calculations was modelled by theJonesndashWilkinsndashLee equation of state e JWL EOS can bewritten in the following form [35]

Pe A 1minusω

R1V1113888 1113889e

minusR1V+ B 1minus

ωR2V

1113888 1113889eminusR2V

+ωEe

V (1)

where Pe is the pressure produced by the detonationproducts from explosive where ω A B R1 and R2 are user-defined input parameters V is the relative volume and Ee isthe internal energy per initial volume as shown in Table 5

324 Air Air was modelled by the material type 9 of LS-DYNA (lowastMAT_NULL) with the Gruneisen equation epressure Pa can be calculated by [35]

Pa C0 + C1μ + C2μ2 + C3μ3 + C4 + C5μ + C6μ2( 1113857Ea

μ 1

Vaminus 1

⎧⎪⎪⎪⎪⎨

⎪⎪⎪⎪⎩

(2)

where C0 C1 C2 C3 C4 C5 and C6 are user-definedconstants ρa is the density of air Va is the relative

volume of air Ea is the internal energy of air as shown inTable 6

33 Numerical Calculation Algorithm Lagrange algorithmhas the priority of less computation time and accuratelydescribing the boundary movement of structure so it isalways used to analyze the explosive detonation Howeverit has a big disadvantage of causing element distortion andeven leads to the termination of calculation when dealingwith the large deformation numerical calculation Inorder to avoid the above problem fluid-solid couplingalgorithm was adopted for the analysis of the explosivedetonation of which ALE algorithm was used for ex-plosive and air and Lagrange algorithm for rock andprotecting pipe e material derivative equation and thegoverning equations of the ALE algorithm can beexpressed as follows [35]

df(X t)

dt

zf(ξ t)

zt+ vi minuswi( 1113857

zf(x t)

zxi

zρzt

ρzυi

zx+ ωi

zρzx

ρzυi

zt+ ρωi

zυi

zxj

zσij

zxj

+ ρfi

ρze

zt σij

zυi

zxj

minuszq

zxj

minus ρωi

ze

zxi

(3)

where f is the physical quantity vi is the velocity of particleX ωi is the velocity of the computational grid xi is theLagrangian coordinate system yi is the Eulerian coordinatesystem ρ is the density v is the particle velocity e is theinternal energy of unit mass σij is the Cauchy stress tensorfi is the body force qi is the heat flux and subscripts i and j

stand for the direction of coordinateAt the same time meshes of explosive and the air were

joined with common nodes and so as to rock and protectingpipe en the fluid-solid coupling was defined between themeshes of the explosive air rock and protecting pipe by thekeyword In addition according to the characteristics ofblasting process the time step of the simulation is 067 andthe computation time is 0004 s

34 Simulation Results Analysis e Postprocessing soft-ware LS-PREPOST was used to draw the diagrams of theevolution law of explosion stress wave and crack propaga-tion of different simulation cases as shown in Figures 9ndash11

In general for regular blasthole blasting the explosionstress uniformly acts on the wall of blasthole and the shapeof blast stress wave is round and then the blast-inducedcrack forms and expands under the blast loading Due to thecharacters of blast loading the gas pressure acting onblasthole wall in all directions can be considered as equiv-alent so the well-distributed blast-induced cracks generatenear the blasthole which is consistent with the classicalblasting theory

Shock and Vibration 7

However by comparing 1 simulation case the blast-induced crack propagation law and the transmission law ofexplosion stress wave of 2 simulation case and 3 simu-lation case were greatly changed under the effect of water jetslot and blasthole wall protection materials On one handblasting energy focus forms at the initial stage of the ex-plosion which promotes the initial microcrack produced atthe direction of water jet slot And nothing but air is in thewater jet slot which caused the formation of low-pressurezone so detonation products have priority to flow along thedirection of water jet slot en the high-pressure and high-velocity gas products wedge into the slot further leading tocrack initiation and extension along the desired direction asshown in Figures 10 and 11 On the other hand as the failureof blasthole wall protectionmaterial makes a large amount ofconsumption of blast energy the formation of microcrack ofthe remaining rock mass was restrained Furthermorethe blasthole wall protection material is in a molten stateduring the blasting which will wedge into the unexpected

microcracks and then the ldquogas edge effectrdquo of gas productwill be greatly weakened So the dual purpose of directionalblast-induced crack propagation and remaining rock massprotection is realized

To further understand the transmission law of blaststress wave and the change regularity of blasting strain underdifferent conditions monitoring points were set in thenumerical simulation model and its schematic diagram isshown in Figure 12 where Dm stands for the distance be-tween the monitoring point and the center of blasthole rbstands for the radius of blasthole and αn is the angle betweentwo lines one is the connection between blasthole center andwater jet slot and the another is the connection betweenblasthole center and monitoring point

Figures 13ndash15 show the P-T curves of different simu-lation cases from which we can see that with the increase ofDm the pressure of different cases almost shows a trend ofgradual decrease but the pressure of different monitoringpoints of different cases shows a different changing trendFor 1 simulation case when Dmrb is certain each P-Tcurve shows the same trend because of the explosion at isbecause the explosion stress uniformly acts on the wall ofblasthole during blasting which is consistent with experi-ment test result For 2 simulation case when αn is 0deg the

Table 3 Parameters of rock

Density (gcm3) Elastic modulus (MPa) Tangent modulus (MPa) Poisson ratio Yield strength (MPa) SRC SRP Failure strain250 225times104 420times103 022 300 0 0 006

Table 4 Parameters of blasthole wall protection material

Density (gcm3) Elastic modulus (MPa) Poisson ratio Yield strength (MPa) SRC SRP Failure strain143 300times103 03 18times10minus1 0 0 01

Table 5 Parameters of explosive and its EOS equation

ρe (gcm3) vD (cmμs) Pcut (MPa) A (MPa) B (MPa) R1 R2 ω

170 083 295times104 855times105 205times104 460 135 025

Table 6 Parameters of air and its EOS equation

ρa (gcm3) C0 C1 C2 C3 C4 C5 C6

120times10minus3 000 000 000 000 040 040 000

Nonreflected boundaryRock

Nonreflected boundary

A

75

150

150

75

Blasthole wall protection material

Explosive

Water jet slot

(a) (b)

Figure 8 Numerical simulation model (a) 3 simulation model (b) enlargement of part A

8 Shock and Vibration

peak value of the measuring point is smaller than that ofregular blasting but the valley value is bigger than that ofregular blasthole blasting at is to say the rock will besubjected to tensile stress As we know the tensile strength ofrock is far less than its compressive strength so the rock isvulnerable to failure [34] which suggest that the existence ofthe water jet slot changed the distribution laws of stress fieldsduring blasting let the blast-induced crack initiation andpropagation in the direction of water jet slot

For 3 simulation case when αn is 0deg though the peakvalue continues to decline valley value is 4040 greaterthan that of 2 simulation case Moreover the action time of

tensile stress of 3 simulation case is much longer than thatof 2 simulation case When αn is 90deg the peak value is2534 and 2966 smaller than that of 2 simulation caseand 1 simulation case respectively which demonstratesthat the existence of blasthole wall protection material hascreated more favorable conditions for the blast-inducedcrack propagation along the direction of water jet slotand the protection of blasthole wall during blasting which isconsistent with the above analysis

Figures 16ndash18 present the effective stress curves of dif-ferent simulation cases For 1 simulation case as the ex-plosion stress uniformly acts on the wall of blasthole during

Blast stress wave Blast-induced crack

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 9 Diagram of blast-induced crack propagation and stress wave transmission of 1 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focus Blast-induced crack

Stress concentration

Blast stress wave

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 10 Diagram of blast-induced crack propagation and stress wave transmission of 2 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focusBlast-induced crack

Stress concentration

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 11 Diagram of blast-induced crack propagation and stress wave transmission of 3 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Shock and Vibration 9

αn

N2-4

N2-3

N2-2

N2-1

N1-110 10 1020

N1-2 N1-3 N1-4

90deg

Dm

rb

Figure 12 Schematic diagram of monitoring point layout

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 13 P-T curve of different monitoring points of 1 simulation case (a) αn 0deg (b) αn 90deg

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

(b)

Figure 14 P-T curve of different monitoring points of 2 simulation case (a) αn 0deg (b) αn 90deg

10 Shock and Vibration

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 15 P-T curve of different monitoring points of 3 simulation case (a) αn 0deg (b) αn 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(b)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(c)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(d)

Figure 16 Effective stress curve of different monitoring points of 1 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 11

blasting the effective stress of each curve shows the sametrend if Dmrb is certain and the effective stress decreasesgradually and becomes stable with the increase of Dmrb For2 simulation case the peak value of effective stress de-creases with the increase of Dmrb and αn at is to say ifDmrb is certain the rock located at different directionsaround the blasthole suffered different effective stress thecloser the rock gets to the direction of water jet the biggerthe effective stress the rock suffered For 3 simulation casethe variation trend of effective stress is similar to that of 2simulation case but the peak value of each effective stresscurve is quite different By comparing each effective stresscurve of 2 simulation case and 3 simulation case we cansee that in the direction of water jet slot the peak value ofeffective stress of 3 simulation case is always bigger thanthat of 2 simulation case However in the direction per-pendicular to the direction of the jet slot the peak value ofeffective stress of 3 simulation case is always smaller than

that of 2 simulation case which indicates that the existenceof blasthole wall protection material is not only very ben-eficial to the ldquoguiding effectrdquo of blast-induced crack prop-agation by water jet slot but also beneficial to reduce blast-induced damage of remaining rock mass

Moreover by comparing Figures 16(d) 17(d) and 18(d)we can see that in the direction of water jet slot the effectivestress of 2 simulation case decreases gradually and whenDmrb is 20 the distribution-evolution law of effective stressis similar to that of 1 simulation case However for 3simulation case when Dmrb is 20 the peak value of effectivestress is bigger than that of 2 simulation case and thegrowing trend of effective stress shows a large fluctuationwhich suggested that the rock suffered the ldquoguiding effectrdquo bywater jet slot In addition in the other direction of blastholethe distribution-evolution law of effective stress is similar tothat of 1 simulation case at is to say the bigger Dmrb isthe weaker the ldquoguiding effectrdquo and ldquoblasthole wall

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 17 Effective stress curve of different monitoring points of 2 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

12 Shock and Vibration

protection effectrdquo by water jet slot and wall protectionmaterial are

4 Conclusions

In summary some conclusions can be summarized asfollows

e experiment test on dynamic blast strain was con-ducted and the results indicated that under the combinedeffect of blasthole wall protection material and water jet slotthe blasting strain fields were changed by comparing withthe regular blasthole blasting In the direction of water jetslot the PSPV was increased by 8500 and in the directionperpendicular to the direction of water jet slot the PSPV wasreduced by 7021

Numerical simulation results suggest that the existence ofwater jet slot and blasthole wall protection material can affectthe distribution and evolution law of explosive stress waveand let the stress concentration occur at the tip of water jet

slot which promotes blast-induced crack propagation alongthe specific direction and minimizes the blast-induceddamage of remaining rock mass Moreover the bigger Dmrb is the weaker the ldquoguiding effectrdquo and ldquoblasthole wallprotection effectrdquo by water jet slot and wall protection ma-terial are

Both the experiment test result and the numericalsimulation results indicated that the existence of blastholewall protection material is not only beneficial to the ldquoguidingeffectrdquo of blast-induced crack propagation of water jet slotbut also beneficial to reduce blast-induced damage ofremaining rock mass

Future research work will be focused on the applicationsin practical engineering of this approach

Data Availability

Readers can access the data supporting the conclusions ofthe study by sending a mail to the corresponding author

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 18 Effective stress curve of different monitoring points of 3 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 13

(e-mail dengfengcqu163com) and all data can be cosh-ared without restriction

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

Financial support for this work was provided by the NaturalScience Foundation of Southwest University of Science andTechnology (18zx7124) In particular the authors thank ME D Y Li and M E F W Yan for their kind help inexperimental investigation and sincere suggestion

References

[1] Z N Zhao X T Feng Y X Xiao et al ldquoMicroseismiccharacteristics and rockburst risk of deep tunnel constructedby different excavation methodsrdquo Chinese Journal of Geo-technical Engineering vol 38 no 5 pp 0867ndash0876 2016

[2] Z C Zhang ldquoControl in blasting engineeringrdquo ChineseJournal of Underground Space and Engineering vol 9 no 5pp 1208ndash1214 2013

[3] Y Wang ldquoStudy of the dynamic fracture effect using slottedcartridge decoupling charge blastingrdquo International Journal ofRock Mechanics and Mining Sciences vol 96 pp 34ndash46 2017

[4] S S Rathore and S Bhandari ldquoControlled fracture growth byblasting while protecting damages to remaining rockrdquo RockMechanics and Rock Engineering vol 40 no 3 pp 317ndash3262007

[5] S H Cho Y Nakamura B Mohanty H S Yang andK Kaneko ldquoNumerical study of fracture plane control inlaboratory-scale blastingrdquo Engineering Fracture Mechanicsvol 75 no 13 pp 3966ndash3984 2008

[6] R S Yang Y B Wang and L Y Yang ldquoDynamic causticexperimental study of crack propagation in two borehole cutblastingrdquo Journal of China University of Mining amp Technologyvol 41 no 6 pp 868ndash872 2012

[7] WM Liang X L Yang and Y Q Yu ldquoResearch on theory ondirectional fracture controlled blastingrdquo Journal of LiaoningTechnical University vol 25 no 5 pp 702ndash704 2006

[8] J S Song Y B Wang X T Gao et al ldquoe mechanism ofdirectional fracture controlled blasting and its applicationrdquoJournal of Mining Science and Technology vol 1 no 1pp 16ndash28 2016

[9] Y Wang ldquoExperimental research on the influence of anempty-hole defect on crack connections between a direc-tionally fractured blast holerdquo Journal of Testing and Evalu-ation vol 45 no 6 pp 2139ndash2150 2017

[10] Z Li W Chen and H Hao ldquoNumerical study of sandwichpanel with a new bi-directional load-self-cancelling (LSC)core under blast loadingrdquo =in-Walled Structures vol 127pp 90ndash101 2018

[11] K Katsuyama H Kiyokawa and K Sassa ldquoControl thegrowth of cracks from a borehole by a new method of smoothblastingrdquo Mining Safety vol 29 pp 16ndash23 1983

[12] W L Fourney D B Barker and D C Holloway ldquoModelstudies of explosive well stimulation techniquesrdquo In-ternational Journal of Rock Mechanics and Mining Sciences ampGeomechanics Abstracts vol 18 no 2 pp 113ndash127 1981

[13] W L Fourney D B Barker and D C Holloway ldquoModelstudies of well stimulation using propellant chargesrdquo

International Journal of Rock Mechanics and Mining Sciencesamp Geomechanics Abstracts vol 20 no 2 pp 91ndash101 1983

[14] B Mohanty ldquoExplosive generated fractures in rock and rocklike materialsrdquo Engineering Fracture Mechanics vol 35 no 4-5 pp 889ndash898 1990

[15] B Mohanty ldquoFracture-plane control blasts with satelliteholesrdquo in Proceedings of 3rd International Symposium on RockFragmentation by Blasting pp 407ndash418 Australasian Instituteof Mining and Metallurgy Parkville Australia August 1990

[16] Y G Du Z C Zhang and T L Li ldquoStudies on mechanicaleffect produced by the V-shaped notch borehole blastingrdquoExplosion and Shock Waves vol 11 pp 26ndash30 1991

[17] Q Zong ldquoeoretical study on the cracking mechanism ofnotched borehole blastingrdquo Coal Mine Blasting vol 1pp 12ndash16 1995

[18] Q Zong ldquoInvestigations into mechanism of crack formationfor grooved hole-well blastingrdquo Chinese Journal of Geo-technical Engineering vol 20 no 1 pp 30ndash33 1998

[19] S H Cho Y Nakamura and K Kaneko ldquoDynamic fractureprocess analysis of rock subjected to a stress wave and gaspressurizationrdquo International Journal of Rock Mechanics andMining Sciences vol 41 no 3 pp 433ndash440 2004

[20] Y Zhang ldquoDynamic numerical simulation for the mechanismof V-shaped notch blastingrdquo Explosive Materials vol 38no 4 pp 1ndash5 2009

[21] R S Yang and Y B Wang ldquoDynamic caustic experiment onfracture behaviors of flawed material induced by pre-notchedblastingrdquo Explosive and Shock Waves vol 36 no 2pp 145ndash152 2016

[22] R S Yang C X Ding L Y Yang P Xu and C Chen ldquoHoledefects affect the dynamic fracture behavior of nearby runningcracksrdquo Shock and Vibration vol 2018 Article ID 58943568 pages 2018

[23] Z W Yue Y Guo X Wang et al ldquoInfluence of empty holeshape on directional fracture controlled blasting of rockrdquoRock and Soil Mechanics vol 37 no 2 pp 376ndash382 2016

[24] Z Yue P Qiu R Yang S Zhang K Yuan and Z Li ldquoStressanalysis of the interaction of a running crack and blastingwaves by caustics methodrdquo Engineering Fracture Mechanicsvol 184 pp 339ndash351 2017

[25] B Chen C Liu and J X Yang ldquoAnalysis and application oncontrolling thick hard roof caving with deep-hole positionpresplitting blastingrdquoAdvances in Civil Engineering vol 2018Article ID 9763137 15 pages 2018

[26] Y H Zhu and X P Xu ldquoDamage control characteristics fornotched blasting based on the damage mechanismrdquo Journal ofChina Coal Society vol 42 no 2 pp 369ndash376 2017

[27] X H Li L Yang J S Wang et al ldquoe natural frequencycharacteristic of the self-excited oscillation pulsed water jetdevicerdquo Journal of China Coal Society vol 25 no 6pp 641ndash644 2000

[28] X H Li Y Y Lu Y Zhao et al ldquoStudy on improving thepermeability of soft coal seam with high pressure pulsed waterjetrdquo Journal of China Coal Society vol 33 no 12 pp 1386ndash1390 2007

[29] Y Kang X C Wang X F Yang et al ldquoNumerical simulationof control blasting with borehole protecting and water jetslotting in soft rock massrdquo Disaster Advances vol 5 no 4pp 933ndash938 2012

[30] J-G Kim and J-J Song ldquoAbrasive water jet cutting methodsfor reducing blast-induced ground vibration in tunnel ex-cavationrdquo International Journal of Rock Mechanics andMining Sciences vol 75 pp 147ndash158 2015

14 Shock and Vibration

[31] Y Kang D D Zheng D F Su et al ldquoModel of directionalshaped blasting assisted with water jet and its numericalsimulationrdquo Journal of Vibration and Shock vol 34pp 182ndash188 2015

[32] D Su Y Kang F Yan D Zheng X Wang and M WeildquoCrack propagation law affected by natural fracture and waterjet slot under blast loadingrdquo Combustion Explosion andShock Waves vol 54 no 6 pp 747ndash756 2018

[33] Y B Wang ldquoRock dynamic fracture characteristics based onNSCB impact methodrdquo Shock and Vibration vol 2018 Ar-ticle ID 3105384 13 pages 2018

[34] J Dai Dynamic Behaviors and Blasting =eory of RockMetallurgical Industry Press Beijing China 2013

[35] LSTC LS-DYNAKeyword Userrsquos Manual Livermore SoftwareTechnology Corporation Livermore CA USA 2007

Shock and Vibration 15

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Page 8: ExperimentalStudyandNumericalSimulationofDynamic Stress ...downloads.hindawi.com/journals/sv/2019/1659175.pdf,kLL jLL xLL L xLL jLL,kLL L L©L, L©Lk L©Lff L©Lx _NF ig E NFE #_#YNIkff©,Ifiig

However by comparing 1 simulation case the blast-induced crack propagation law and the transmission law ofexplosion stress wave of 2 simulation case and 3 simu-lation case were greatly changed under the effect of water jetslot and blasthole wall protection materials On one handblasting energy focus forms at the initial stage of the ex-plosion which promotes the initial microcrack produced atthe direction of water jet slot And nothing but air is in thewater jet slot which caused the formation of low-pressurezone so detonation products have priority to flow along thedirection of water jet slot en the high-pressure and high-velocity gas products wedge into the slot further leading tocrack initiation and extension along the desired direction asshown in Figures 10 and 11 On the other hand as the failureof blasthole wall protectionmaterial makes a large amount ofconsumption of blast energy the formation of microcrack ofthe remaining rock mass was restrained Furthermorethe blasthole wall protection material is in a molten stateduring the blasting which will wedge into the unexpected

microcracks and then the ldquogas edge effectrdquo of gas productwill be greatly weakened So the dual purpose of directionalblast-induced crack propagation and remaining rock massprotection is realized

To further understand the transmission law of blaststress wave and the change regularity of blasting strain underdifferent conditions monitoring points were set in thenumerical simulation model and its schematic diagram isshown in Figure 12 where Dm stands for the distance be-tween the monitoring point and the center of blasthole rbstands for the radius of blasthole and αn is the angle betweentwo lines one is the connection between blasthole center andwater jet slot and the another is the connection betweenblasthole center and monitoring point

Figures 13ndash15 show the P-T curves of different simu-lation cases from which we can see that with the increase ofDm the pressure of different cases almost shows a trend ofgradual decrease but the pressure of different monitoringpoints of different cases shows a different changing trendFor 1 simulation case when Dmrb is certain each P-Tcurve shows the same trend because of the explosion at isbecause the explosion stress uniformly acts on the wall ofblasthole during blasting which is consistent with experi-ment test result For 2 simulation case when αn is 0deg the

Table 3 Parameters of rock

Density (gcm3) Elastic modulus (MPa) Tangent modulus (MPa) Poisson ratio Yield strength (MPa) SRC SRP Failure strain250 225times104 420times103 022 300 0 0 006

Table 4 Parameters of blasthole wall protection material

Density (gcm3) Elastic modulus (MPa) Poisson ratio Yield strength (MPa) SRC SRP Failure strain143 300times103 03 18times10minus1 0 0 01

Table 5 Parameters of explosive and its EOS equation

ρe (gcm3) vD (cmμs) Pcut (MPa) A (MPa) B (MPa) R1 R2 ω

170 083 295times104 855times105 205times104 460 135 025

Table 6 Parameters of air and its EOS equation

ρa (gcm3) C0 C1 C2 C3 C4 C5 C6

120times10minus3 000 000 000 000 040 040 000

Nonreflected boundaryRock

Nonreflected boundary

A

75

150

150

75

Blasthole wall protection material

Explosive

Water jet slot

(a) (b)

Figure 8 Numerical simulation model (a) 3 simulation model (b) enlargement of part A

8 Shock and Vibration

peak value of the measuring point is smaller than that ofregular blasting but the valley value is bigger than that ofregular blasthole blasting at is to say the rock will besubjected to tensile stress As we know the tensile strength ofrock is far less than its compressive strength so the rock isvulnerable to failure [34] which suggest that the existence ofthe water jet slot changed the distribution laws of stress fieldsduring blasting let the blast-induced crack initiation andpropagation in the direction of water jet slot

For 3 simulation case when αn is 0deg though the peakvalue continues to decline valley value is 4040 greaterthan that of 2 simulation case Moreover the action time of

tensile stress of 3 simulation case is much longer than thatof 2 simulation case When αn is 90deg the peak value is2534 and 2966 smaller than that of 2 simulation caseand 1 simulation case respectively which demonstratesthat the existence of blasthole wall protection material hascreated more favorable conditions for the blast-inducedcrack propagation along the direction of water jet slotand the protection of blasthole wall during blasting which isconsistent with the above analysis

Figures 16ndash18 present the effective stress curves of dif-ferent simulation cases For 1 simulation case as the ex-plosion stress uniformly acts on the wall of blasthole during

Blast stress wave Blast-induced crack

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 9 Diagram of blast-induced crack propagation and stress wave transmission of 1 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focus Blast-induced crack

Stress concentration

Blast stress wave

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 10 Diagram of blast-induced crack propagation and stress wave transmission of 2 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focusBlast-induced crack

Stress concentration

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 11 Diagram of blast-induced crack propagation and stress wave transmission of 3 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Shock and Vibration 9

αn

N2-4

N2-3

N2-2

N2-1

N1-110 10 1020

N1-2 N1-3 N1-4

90deg

Dm

rb

Figure 12 Schematic diagram of monitoring point layout

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 13 P-T curve of different monitoring points of 1 simulation case (a) αn 0deg (b) αn 90deg

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

(b)

Figure 14 P-T curve of different monitoring points of 2 simulation case (a) αn 0deg (b) αn 90deg

10 Shock and Vibration

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 15 P-T curve of different monitoring points of 3 simulation case (a) αn 0deg (b) αn 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(b)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(c)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(d)

Figure 16 Effective stress curve of different monitoring points of 1 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 11

blasting the effective stress of each curve shows the sametrend if Dmrb is certain and the effective stress decreasesgradually and becomes stable with the increase of Dmrb For2 simulation case the peak value of effective stress de-creases with the increase of Dmrb and αn at is to say ifDmrb is certain the rock located at different directionsaround the blasthole suffered different effective stress thecloser the rock gets to the direction of water jet the biggerthe effective stress the rock suffered For 3 simulation casethe variation trend of effective stress is similar to that of 2simulation case but the peak value of each effective stresscurve is quite different By comparing each effective stresscurve of 2 simulation case and 3 simulation case we cansee that in the direction of water jet slot the peak value ofeffective stress of 3 simulation case is always bigger thanthat of 2 simulation case However in the direction per-pendicular to the direction of the jet slot the peak value ofeffective stress of 3 simulation case is always smaller than

that of 2 simulation case which indicates that the existenceof blasthole wall protection material is not only very ben-eficial to the ldquoguiding effectrdquo of blast-induced crack prop-agation by water jet slot but also beneficial to reduce blast-induced damage of remaining rock mass

Moreover by comparing Figures 16(d) 17(d) and 18(d)we can see that in the direction of water jet slot the effectivestress of 2 simulation case decreases gradually and whenDmrb is 20 the distribution-evolution law of effective stressis similar to that of 1 simulation case However for 3simulation case when Dmrb is 20 the peak value of effectivestress is bigger than that of 2 simulation case and thegrowing trend of effective stress shows a large fluctuationwhich suggested that the rock suffered the ldquoguiding effectrdquo bywater jet slot In addition in the other direction of blastholethe distribution-evolution law of effective stress is similar tothat of 1 simulation case at is to say the bigger Dmrb isthe weaker the ldquoguiding effectrdquo and ldquoblasthole wall

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 17 Effective stress curve of different monitoring points of 2 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

12 Shock and Vibration

protection effectrdquo by water jet slot and wall protectionmaterial are

4 Conclusions

In summary some conclusions can be summarized asfollows

e experiment test on dynamic blast strain was con-ducted and the results indicated that under the combinedeffect of blasthole wall protection material and water jet slotthe blasting strain fields were changed by comparing withthe regular blasthole blasting In the direction of water jetslot the PSPV was increased by 8500 and in the directionperpendicular to the direction of water jet slot the PSPV wasreduced by 7021

Numerical simulation results suggest that the existence ofwater jet slot and blasthole wall protection material can affectthe distribution and evolution law of explosive stress waveand let the stress concentration occur at the tip of water jet

slot which promotes blast-induced crack propagation alongthe specific direction and minimizes the blast-induceddamage of remaining rock mass Moreover the bigger Dmrb is the weaker the ldquoguiding effectrdquo and ldquoblasthole wallprotection effectrdquo by water jet slot and wall protection ma-terial are

Both the experiment test result and the numericalsimulation results indicated that the existence of blastholewall protection material is not only beneficial to the ldquoguidingeffectrdquo of blast-induced crack propagation of water jet slotbut also beneficial to reduce blast-induced damage ofremaining rock mass

Future research work will be focused on the applicationsin practical engineering of this approach

Data Availability

Readers can access the data supporting the conclusions ofthe study by sending a mail to the corresponding author

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 18 Effective stress curve of different monitoring points of 3 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 13

(e-mail dengfengcqu163com) and all data can be cosh-ared without restriction

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

Financial support for this work was provided by the NaturalScience Foundation of Southwest University of Science andTechnology (18zx7124) In particular the authors thank ME D Y Li and M E F W Yan for their kind help inexperimental investigation and sincere suggestion

References

[1] Z N Zhao X T Feng Y X Xiao et al ldquoMicroseismiccharacteristics and rockburst risk of deep tunnel constructedby different excavation methodsrdquo Chinese Journal of Geo-technical Engineering vol 38 no 5 pp 0867ndash0876 2016

[2] Z C Zhang ldquoControl in blasting engineeringrdquo ChineseJournal of Underground Space and Engineering vol 9 no 5pp 1208ndash1214 2013

[3] Y Wang ldquoStudy of the dynamic fracture effect using slottedcartridge decoupling charge blastingrdquo International Journal ofRock Mechanics and Mining Sciences vol 96 pp 34ndash46 2017

[4] S S Rathore and S Bhandari ldquoControlled fracture growth byblasting while protecting damages to remaining rockrdquo RockMechanics and Rock Engineering vol 40 no 3 pp 317ndash3262007

[5] S H Cho Y Nakamura B Mohanty H S Yang andK Kaneko ldquoNumerical study of fracture plane control inlaboratory-scale blastingrdquo Engineering Fracture Mechanicsvol 75 no 13 pp 3966ndash3984 2008

[6] R S Yang Y B Wang and L Y Yang ldquoDynamic causticexperimental study of crack propagation in two borehole cutblastingrdquo Journal of China University of Mining amp Technologyvol 41 no 6 pp 868ndash872 2012

[7] WM Liang X L Yang and Y Q Yu ldquoResearch on theory ondirectional fracture controlled blastingrdquo Journal of LiaoningTechnical University vol 25 no 5 pp 702ndash704 2006

[8] J S Song Y B Wang X T Gao et al ldquoe mechanism ofdirectional fracture controlled blasting and its applicationrdquoJournal of Mining Science and Technology vol 1 no 1pp 16ndash28 2016

[9] Y Wang ldquoExperimental research on the influence of anempty-hole defect on crack connections between a direc-tionally fractured blast holerdquo Journal of Testing and Evalu-ation vol 45 no 6 pp 2139ndash2150 2017

[10] Z Li W Chen and H Hao ldquoNumerical study of sandwichpanel with a new bi-directional load-self-cancelling (LSC)core under blast loadingrdquo =in-Walled Structures vol 127pp 90ndash101 2018

[11] K Katsuyama H Kiyokawa and K Sassa ldquoControl thegrowth of cracks from a borehole by a new method of smoothblastingrdquo Mining Safety vol 29 pp 16ndash23 1983

[12] W L Fourney D B Barker and D C Holloway ldquoModelstudies of explosive well stimulation techniquesrdquo In-ternational Journal of Rock Mechanics and Mining Sciences ampGeomechanics Abstracts vol 18 no 2 pp 113ndash127 1981

[13] W L Fourney D B Barker and D C Holloway ldquoModelstudies of well stimulation using propellant chargesrdquo

International Journal of Rock Mechanics and Mining Sciencesamp Geomechanics Abstracts vol 20 no 2 pp 91ndash101 1983

[14] B Mohanty ldquoExplosive generated fractures in rock and rocklike materialsrdquo Engineering Fracture Mechanics vol 35 no 4-5 pp 889ndash898 1990

[15] B Mohanty ldquoFracture-plane control blasts with satelliteholesrdquo in Proceedings of 3rd International Symposium on RockFragmentation by Blasting pp 407ndash418 Australasian Instituteof Mining and Metallurgy Parkville Australia August 1990

[16] Y G Du Z C Zhang and T L Li ldquoStudies on mechanicaleffect produced by the V-shaped notch borehole blastingrdquoExplosion and Shock Waves vol 11 pp 26ndash30 1991

[17] Q Zong ldquoeoretical study on the cracking mechanism ofnotched borehole blastingrdquo Coal Mine Blasting vol 1pp 12ndash16 1995

[18] Q Zong ldquoInvestigations into mechanism of crack formationfor grooved hole-well blastingrdquo Chinese Journal of Geo-technical Engineering vol 20 no 1 pp 30ndash33 1998

[19] S H Cho Y Nakamura and K Kaneko ldquoDynamic fractureprocess analysis of rock subjected to a stress wave and gaspressurizationrdquo International Journal of Rock Mechanics andMining Sciences vol 41 no 3 pp 433ndash440 2004

[20] Y Zhang ldquoDynamic numerical simulation for the mechanismof V-shaped notch blastingrdquo Explosive Materials vol 38no 4 pp 1ndash5 2009

[21] R S Yang and Y B Wang ldquoDynamic caustic experiment onfracture behaviors of flawed material induced by pre-notchedblastingrdquo Explosive and Shock Waves vol 36 no 2pp 145ndash152 2016

[22] R S Yang C X Ding L Y Yang P Xu and C Chen ldquoHoledefects affect the dynamic fracture behavior of nearby runningcracksrdquo Shock and Vibration vol 2018 Article ID 58943568 pages 2018

[23] Z W Yue Y Guo X Wang et al ldquoInfluence of empty holeshape on directional fracture controlled blasting of rockrdquoRock and Soil Mechanics vol 37 no 2 pp 376ndash382 2016

[24] Z Yue P Qiu R Yang S Zhang K Yuan and Z Li ldquoStressanalysis of the interaction of a running crack and blastingwaves by caustics methodrdquo Engineering Fracture Mechanicsvol 184 pp 339ndash351 2017

[25] B Chen C Liu and J X Yang ldquoAnalysis and application oncontrolling thick hard roof caving with deep-hole positionpresplitting blastingrdquoAdvances in Civil Engineering vol 2018Article ID 9763137 15 pages 2018

[26] Y H Zhu and X P Xu ldquoDamage control characteristics fornotched blasting based on the damage mechanismrdquo Journal ofChina Coal Society vol 42 no 2 pp 369ndash376 2017

[27] X H Li L Yang J S Wang et al ldquoe natural frequencycharacteristic of the self-excited oscillation pulsed water jetdevicerdquo Journal of China Coal Society vol 25 no 6pp 641ndash644 2000

[28] X H Li Y Y Lu Y Zhao et al ldquoStudy on improving thepermeability of soft coal seam with high pressure pulsed waterjetrdquo Journal of China Coal Society vol 33 no 12 pp 1386ndash1390 2007

[29] Y Kang X C Wang X F Yang et al ldquoNumerical simulationof control blasting with borehole protecting and water jetslotting in soft rock massrdquo Disaster Advances vol 5 no 4pp 933ndash938 2012

[30] J-G Kim and J-J Song ldquoAbrasive water jet cutting methodsfor reducing blast-induced ground vibration in tunnel ex-cavationrdquo International Journal of Rock Mechanics andMining Sciences vol 75 pp 147ndash158 2015

14 Shock and Vibration

[31] Y Kang D D Zheng D F Su et al ldquoModel of directionalshaped blasting assisted with water jet and its numericalsimulationrdquo Journal of Vibration and Shock vol 34pp 182ndash188 2015

[32] D Su Y Kang F Yan D Zheng X Wang and M WeildquoCrack propagation law affected by natural fracture and waterjet slot under blast loadingrdquo Combustion Explosion andShock Waves vol 54 no 6 pp 747ndash756 2018

[33] Y B Wang ldquoRock dynamic fracture characteristics based onNSCB impact methodrdquo Shock and Vibration vol 2018 Ar-ticle ID 3105384 13 pages 2018

[34] J Dai Dynamic Behaviors and Blasting =eory of RockMetallurgical Industry Press Beijing China 2013

[35] LSTC LS-DYNAKeyword Userrsquos Manual Livermore SoftwareTechnology Corporation Livermore CA USA 2007

Shock and Vibration 15

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Page 9: ExperimentalStudyandNumericalSimulationofDynamic Stress ...downloads.hindawi.com/journals/sv/2019/1659175.pdf,kLL jLL xLL L xLL jLL,kLL L L©L, L©Lk L©Lff L©Lx _NF ig E NFE #_#YNIkff©,Ifiig

peak value of the measuring point is smaller than that ofregular blasting but the valley value is bigger than that ofregular blasthole blasting at is to say the rock will besubjected to tensile stress As we know the tensile strength ofrock is far less than its compressive strength so the rock isvulnerable to failure [34] which suggest that the existence ofthe water jet slot changed the distribution laws of stress fieldsduring blasting let the blast-induced crack initiation andpropagation in the direction of water jet slot

For 3 simulation case when αn is 0deg though the peakvalue continues to decline valley value is 4040 greaterthan that of 2 simulation case Moreover the action time of

tensile stress of 3 simulation case is much longer than thatof 2 simulation case When αn is 90deg the peak value is2534 and 2966 smaller than that of 2 simulation caseand 1 simulation case respectively which demonstratesthat the existence of blasthole wall protection material hascreated more favorable conditions for the blast-inducedcrack propagation along the direction of water jet slotand the protection of blasthole wall during blasting which isconsistent with the above analysis

Figures 16ndash18 present the effective stress curves of dif-ferent simulation cases For 1 simulation case as the ex-plosion stress uniformly acts on the wall of blasthole during

Blast stress wave Blast-induced crack

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 9 Diagram of blast-induced crack propagation and stress wave transmission of 1 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focus Blast-induced crack

Stress concentration

Blast stress wave

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 10 Diagram of blast-induced crack propagation and stress wave transmission of 2 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Blast energy focusBlast-induced crack

Stress concentration

Fringe levels3000e ndash 032700e ndash 032400e ndash 032100e ndash 031800e ndash 031500e ndash 031200e ndash 039000e ndash 046000e ndash 043000e ndash 04

ndash3253e ndash 19ndash3000e ndash 04ndash6000e ndash 04ndash9000e ndash 04ndash1200e ndash 03ndash1500e ndash 03ndash1800e ndash 03ndash2100e ndash 03ndash2400e ndash 03ndash2700e ndash 03ndash3000e ndash 03

(a) (b) (c) (d)

Figure 11 Diagram of blast-induced crack propagation and stress wave transmission of 3 simulation case (a) t 20 μs (b) t 120 μs(c) t 240 μs and (d) t 460 μs

Shock and Vibration 9

αn

N2-4

N2-3

N2-2

N2-1

N1-110 10 1020

N1-2 N1-3 N1-4

90deg

Dm

rb

Figure 12 Schematic diagram of monitoring point layout

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 13 P-T curve of different monitoring points of 1 simulation case (a) αn 0deg (b) αn 90deg

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

(b)

Figure 14 P-T curve of different monitoring points of 2 simulation case (a) αn 0deg (b) αn 90deg

10 Shock and Vibration

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 15 P-T curve of different monitoring points of 3 simulation case (a) αn 0deg (b) αn 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(b)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(c)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(d)

Figure 16 Effective stress curve of different monitoring points of 1 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 11

blasting the effective stress of each curve shows the sametrend if Dmrb is certain and the effective stress decreasesgradually and becomes stable with the increase of Dmrb For2 simulation case the peak value of effective stress de-creases with the increase of Dmrb and αn at is to say ifDmrb is certain the rock located at different directionsaround the blasthole suffered different effective stress thecloser the rock gets to the direction of water jet the biggerthe effective stress the rock suffered For 3 simulation casethe variation trend of effective stress is similar to that of 2simulation case but the peak value of each effective stresscurve is quite different By comparing each effective stresscurve of 2 simulation case and 3 simulation case we cansee that in the direction of water jet slot the peak value ofeffective stress of 3 simulation case is always bigger thanthat of 2 simulation case However in the direction per-pendicular to the direction of the jet slot the peak value ofeffective stress of 3 simulation case is always smaller than

that of 2 simulation case which indicates that the existenceof blasthole wall protection material is not only very ben-eficial to the ldquoguiding effectrdquo of blast-induced crack prop-agation by water jet slot but also beneficial to reduce blast-induced damage of remaining rock mass

Moreover by comparing Figures 16(d) 17(d) and 18(d)we can see that in the direction of water jet slot the effectivestress of 2 simulation case decreases gradually and whenDmrb is 20 the distribution-evolution law of effective stressis similar to that of 1 simulation case However for 3simulation case when Dmrb is 20 the peak value of effectivestress is bigger than that of 2 simulation case and thegrowing trend of effective stress shows a large fluctuationwhich suggested that the rock suffered the ldquoguiding effectrdquo bywater jet slot In addition in the other direction of blastholethe distribution-evolution law of effective stress is similar tothat of 1 simulation case at is to say the bigger Dmrb isthe weaker the ldquoguiding effectrdquo and ldquoblasthole wall

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 17 Effective stress curve of different monitoring points of 2 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

12 Shock and Vibration

protection effectrdquo by water jet slot and wall protectionmaterial are

4 Conclusions

In summary some conclusions can be summarized asfollows

e experiment test on dynamic blast strain was con-ducted and the results indicated that under the combinedeffect of blasthole wall protection material and water jet slotthe blasting strain fields were changed by comparing withthe regular blasthole blasting In the direction of water jetslot the PSPV was increased by 8500 and in the directionperpendicular to the direction of water jet slot the PSPV wasreduced by 7021

Numerical simulation results suggest that the existence ofwater jet slot and blasthole wall protection material can affectthe distribution and evolution law of explosive stress waveand let the stress concentration occur at the tip of water jet

slot which promotes blast-induced crack propagation alongthe specific direction and minimizes the blast-induceddamage of remaining rock mass Moreover the bigger Dmrb is the weaker the ldquoguiding effectrdquo and ldquoblasthole wallprotection effectrdquo by water jet slot and wall protection ma-terial are

Both the experiment test result and the numericalsimulation results indicated that the existence of blastholewall protection material is not only beneficial to the ldquoguidingeffectrdquo of blast-induced crack propagation of water jet slotbut also beneficial to reduce blast-induced damage ofremaining rock mass

Future research work will be focused on the applicationsin practical engineering of this approach

Data Availability

Readers can access the data supporting the conclusions ofthe study by sending a mail to the corresponding author

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 18 Effective stress curve of different monitoring points of 3 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 13

(e-mail dengfengcqu163com) and all data can be cosh-ared without restriction

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

Financial support for this work was provided by the NaturalScience Foundation of Southwest University of Science andTechnology (18zx7124) In particular the authors thank ME D Y Li and M E F W Yan for their kind help inexperimental investigation and sincere suggestion

References

[1] Z N Zhao X T Feng Y X Xiao et al ldquoMicroseismiccharacteristics and rockburst risk of deep tunnel constructedby different excavation methodsrdquo Chinese Journal of Geo-technical Engineering vol 38 no 5 pp 0867ndash0876 2016

[2] Z C Zhang ldquoControl in blasting engineeringrdquo ChineseJournal of Underground Space and Engineering vol 9 no 5pp 1208ndash1214 2013

[3] Y Wang ldquoStudy of the dynamic fracture effect using slottedcartridge decoupling charge blastingrdquo International Journal ofRock Mechanics and Mining Sciences vol 96 pp 34ndash46 2017

[4] S S Rathore and S Bhandari ldquoControlled fracture growth byblasting while protecting damages to remaining rockrdquo RockMechanics and Rock Engineering vol 40 no 3 pp 317ndash3262007

[5] S H Cho Y Nakamura B Mohanty H S Yang andK Kaneko ldquoNumerical study of fracture plane control inlaboratory-scale blastingrdquo Engineering Fracture Mechanicsvol 75 no 13 pp 3966ndash3984 2008

[6] R S Yang Y B Wang and L Y Yang ldquoDynamic causticexperimental study of crack propagation in two borehole cutblastingrdquo Journal of China University of Mining amp Technologyvol 41 no 6 pp 868ndash872 2012

[7] WM Liang X L Yang and Y Q Yu ldquoResearch on theory ondirectional fracture controlled blastingrdquo Journal of LiaoningTechnical University vol 25 no 5 pp 702ndash704 2006

[8] J S Song Y B Wang X T Gao et al ldquoe mechanism ofdirectional fracture controlled blasting and its applicationrdquoJournal of Mining Science and Technology vol 1 no 1pp 16ndash28 2016

[9] Y Wang ldquoExperimental research on the influence of anempty-hole defect on crack connections between a direc-tionally fractured blast holerdquo Journal of Testing and Evalu-ation vol 45 no 6 pp 2139ndash2150 2017

[10] Z Li W Chen and H Hao ldquoNumerical study of sandwichpanel with a new bi-directional load-self-cancelling (LSC)core under blast loadingrdquo =in-Walled Structures vol 127pp 90ndash101 2018

[11] K Katsuyama H Kiyokawa and K Sassa ldquoControl thegrowth of cracks from a borehole by a new method of smoothblastingrdquo Mining Safety vol 29 pp 16ndash23 1983

[12] W L Fourney D B Barker and D C Holloway ldquoModelstudies of explosive well stimulation techniquesrdquo In-ternational Journal of Rock Mechanics and Mining Sciences ampGeomechanics Abstracts vol 18 no 2 pp 113ndash127 1981

[13] W L Fourney D B Barker and D C Holloway ldquoModelstudies of well stimulation using propellant chargesrdquo

International Journal of Rock Mechanics and Mining Sciencesamp Geomechanics Abstracts vol 20 no 2 pp 91ndash101 1983

[14] B Mohanty ldquoExplosive generated fractures in rock and rocklike materialsrdquo Engineering Fracture Mechanics vol 35 no 4-5 pp 889ndash898 1990

[15] B Mohanty ldquoFracture-plane control blasts with satelliteholesrdquo in Proceedings of 3rd International Symposium on RockFragmentation by Blasting pp 407ndash418 Australasian Instituteof Mining and Metallurgy Parkville Australia August 1990

[16] Y G Du Z C Zhang and T L Li ldquoStudies on mechanicaleffect produced by the V-shaped notch borehole blastingrdquoExplosion and Shock Waves vol 11 pp 26ndash30 1991

[17] Q Zong ldquoeoretical study on the cracking mechanism ofnotched borehole blastingrdquo Coal Mine Blasting vol 1pp 12ndash16 1995

[18] Q Zong ldquoInvestigations into mechanism of crack formationfor grooved hole-well blastingrdquo Chinese Journal of Geo-technical Engineering vol 20 no 1 pp 30ndash33 1998

[19] S H Cho Y Nakamura and K Kaneko ldquoDynamic fractureprocess analysis of rock subjected to a stress wave and gaspressurizationrdquo International Journal of Rock Mechanics andMining Sciences vol 41 no 3 pp 433ndash440 2004

[20] Y Zhang ldquoDynamic numerical simulation for the mechanismof V-shaped notch blastingrdquo Explosive Materials vol 38no 4 pp 1ndash5 2009

[21] R S Yang and Y B Wang ldquoDynamic caustic experiment onfracture behaviors of flawed material induced by pre-notchedblastingrdquo Explosive and Shock Waves vol 36 no 2pp 145ndash152 2016

[22] R S Yang C X Ding L Y Yang P Xu and C Chen ldquoHoledefects affect the dynamic fracture behavior of nearby runningcracksrdquo Shock and Vibration vol 2018 Article ID 58943568 pages 2018

[23] Z W Yue Y Guo X Wang et al ldquoInfluence of empty holeshape on directional fracture controlled blasting of rockrdquoRock and Soil Mechanics vol 37 no 2 pp 376ndash382 2016

[24] Z Yue P Qiu R Yang S Zhang K Yuan and Z Li ldquoStressanalysis of the interaction of a running crack and blastingwaves by caustics methodrdquo Engineering Fracture Mechanicsvol 184 pp 339ndash351 2017

[25] B Chen C Liu and J X Yang ldquoAnalysis and application oncontrolling thick hard roof caving with deep-hole positionpresplitting blastingrdquoAdvances in Civil Engineering vol 2018Article ID 9763137 15 pages 2018

[26] Y H Zhu and X P Xu ldquoDamage control characteristics fornotched blasting based on the damage mechanismrdquo Journal ofChina Coal Society vol 42 no 2 pp 369ndash376 2017

[27] X H Li L Yang J S Wang et al ldquoe natural frequencycharacteristic of the self-excited oscillation pulsed water jetdevicerdquo Journal of China Coal Society vol 25 no 6pp 641ndash644 2000

[28] X H Li Y Y Lu Y Zhao et al ldquoStudy on improving thepermeability of soft coal seam with high pressure pulsed waterjetrdquo Journal of China Coal Society vol 33 no 12 pp 1386ndash1390 2007

[29] Y Kang X C Wang X F Yang et al ldquoNumerical simulationof control blasting with borehole protecting and water jetslotting in soft rock massrdquo Disaster Advances vol 5 no 4pp 933ndash938 2012

[30] J-G Kim and J-J Song ldquoAbrasive water jet cutting methodsfor reducing blast-induced ground vibration in tunnel ex-cavationrdquo International Journal of Rock Mechanics andMining Sciences vol 75 pp 147ndash158 2015

14 Shock and Vibration

[31] Y Kang D D Zheng D F Su et al ldquoModel of directionalshaped blasting assisted with water jet and its numericalsimulationrdquo Journal of Vibration and Shock vol 34pp 182ndash188 2015

[32] D Su Y Kang F Yan D Zheng X Wang and M WeildquoCrack propagation law affected by natural fracture and waterjet slot under blast loadingrdquo Combustion Explosion andShock Waves vol 54 no 6 pp 747ndash756 2018

[33] Y B Wang ldquoRock dynamic fracture characteristics based onNSCB impact methodrdquo Shock and Vibration vol 2018 Ar-ticle ID 3105384 13 pages 2018

[34] J Dai Dynamic Behaviors and Blasting =eory of RockMetallurgical Industry Press Beijing China 2013

[35] LSTC LS-DYNAKeyword Userrsquos Manual Livermore SoftwareTechnology Corporation Livermore CA USA 2007

Shock and Vibration 15

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Shock and Vibration

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Submit your manuscripts atwwwhindawicom

Page 10: ExperimentalStudyandNumericalSimulationofDynamic Stress ...downloads.hindawi.com/journals/sv/2019/1659175.pdf,kLL jLL xLL L xLL jLL,kLL L L©L, L©Lk L©Lff L©Lx _NF ig E NFE #_#YNIkff©,Ifiig

αn

N2-4

N2-3

N2-2

N2-1

N1-110 10 1020

N1-2 N1-3 N1-4

90deg

Dm

rb

Figure 12 Schematic diagram of monitoring point layout

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 13 P-T curve of different monitoring points of 1 simulation case (a) αn 0deg (b) αn 90deg

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

(b)

Figure 14 P-T curve of different monitoring points of 2 simulation case (a) αn 0deg (b) αn 90deg

10 Shock and Vibration

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 15 P-T curve of different monitoring points of 3 simulation case (a) αn 0deg (b) αn 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(b)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(c)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(d)

Figure 16 Effective stress curve of different monitoring points of 1 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 11

blasting the effective stress of each curve shows the sametrend if Dmrb is certain and the effective stress decreasesgradually and becomes stable with the increase of Dmrb For2 simulation case the peak value of effective stress de-creases with the increase of Dmrb and αn at is to say ifDmrb is certain the rock located at different directionsaround the blasthole suffered different effective stress thecloser the rock gets to the direction of water jet the biggerthe effective stress the rock suffered For 3 simulation casethe variation trend of effective stress is similar to that of 2simulation case but the peak value of each effective stresscurve is quite different By comparing each effective stresscurve of 2 simulation case and 3 simulation case we cansee that in the direction of water jet slot the peak value ofeffective stress of 3 simulation case is always bigger thanthat of 2 simulation case However in the direction per-pendicular to the direction of the jet slot the peak value ofeffective stress of 3 simulation case is always smaller than

that of 2 simulation case which indicates that the existenceof blasthole wall protection material is not only very ben-eficial to the ldquoguiding effectrdquo of blast-induced crack prop-agation by water jet slot but also beneficial to reduce blast-induced damage of remaining rock mass

Moreover by comparing Figures 16(d) 17(d) and 18(d)we can see that in the direction of water jet slot the effectivestress of 2 simulation case decreases gradually and whenDmrb is 20 the distribution-evolution law of effective stressis similar to that of 1 simulation case However for 3simulation case when Dmrb is 20 the peak value of effectivestress is bigger than that of 2 simulation case and thegrowing trend of effective stress shows a large fluctuationwhich suggested that the rock suffered the ldquoguiding effectrdquo bywater jet slot In addition in the other direction of blastholethe distribution-evolution law of effective stress is similar tothat of 1 simulation case at is to say the bigger Dmrb isthe weaker the ldquoguiding effectrdquo and ldquoblasthole wall

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 17 Effective stress curve of different monitoring points of 2 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

12 Shock and Vibration

protection effectrdquo by water jet slot and wall protectionmaterial are

4 Conclusions

In summary some conclusions can be summarized asfollows

e experiment test on dynamic blast strain was con-ducted and the results indicated that under the combinedeffect of blasthole wall protection material and water jet slotthe blasting strain fields were changed by comparing withthe regular blasthole blasting In the direction of water jetslot the PSPV was increased by 8500 and in the directionperpendicular to the direction of water jet slot the PSPV wasreduced by 7021

Numerical simulation results suggest that the existence ofwater jet slot and blasthole wall protection material can affectthe distribution and evolution law of explosive stress waveand let the stress concentration occur at the tip of water jet

slot which promotes blast-induced crack propagation alongthe specific direction and minimizes the blast-induceddamage of remaining rock mass Moreover the bigger Dmrb is the weaker the ldquoguiding effectrdquo and ldquoblasthole wallprotection effectrdquo by water jet slot and wall protection ma-terial are

Both the experiment test result and the numericalsimulation results indicated that the existence of blastholewall protection material is not only beneficial to the ldquoguidingeffectrdquo of blast-induced crack propagation of water jet slotbut also beneficial to reduce blast-induced damage ofremaining rock mass

Future research work will be focused on the applicationsin practical engineering of this approach

Data Availability

Readers can access the data supporting the conclusions ofthe study by sending a mail to the corresponding author

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 18 Effective stress curve of different monitoring points of 3 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 13

(e-mail dengfengcqu163com) and all data can be cosh-ared without restriction

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

Financial support for this work was provided by the NaturalScience Foundation of Southwest University of Science andTechnology (18zx7124) In particular the authors thank ME D Y Li and M E F W Yan for their kind help inexperimental investigation and sincere suggestion

References

[1] Z N Zhao X T Feng Y X Xiao et al ldquoMicroseismiccharacteristics and rockburst risk of deep tunnel constructedby different excavation methodsrdquo Chinese Journal of Geo-technical Engineering vol 38 no 5 pp 0867ndash0876 2016

[2] Z C Zhang ldquoControl in blasting engineeringrdquo ChineseJournal of Underground Space and Engineering vol 9 no 5pp 1208ndash1214 2013

[3] Y Wang ldquoStudy of the dynamic fracture effect using slottedcartridge decoupling charge blastingrdquo International Journal ofRock Mechanics and Mining Sciences vol 96 pp 34ndash46 2017

[4] S S Rathore and S Bhandari ldquoControlled fracture growth byblasting while protecting damages to remaining rockrdquo RockMechanics and Rock Engineering vol 40 no 3 pp 317ndash3262007

[5] S H Cho Y Nakamura B Mohanty H S Yang andK Kaneko ldquoNumerical study of fracture plane control inlaboratory-scale blastingrdquo Engineering Fracture Mechanicsvol 75 no 13 pp 3966ndash3984 2008

[6] R S Yang Y B Wang and L Y Yang ldquoDynamic causticexperimental study of crack propagation in two borehole cutblastingrdquo Journal of China University of Mining amp Technologyvol 41 no 6 pp 868ndash872 2012

[7] WM Liang X L Yang and Y Q Yu ldquoResearch on theory ondirectional fracture controlled blastingrdquo Journal of LiaoningTechnical University vol 25 no 5 pp 702ndash704 2006

[8] J S Song Y B Wang X T Gao et al ldquoe mechanism ofdirectional fracture controlled blasting and its applicationrdquoJournal of Mining Science and Technology vol 1 no 1pp 16ndash28 2016

[9] Y Wang ldquoExperimental research on the influence of anempty-hole defect on crack connections between a direc-tionally fractured blast holerdquo Journal of Testing and Evalu-ation vol 45 no 6 pp 2139ndash2150 2017

[10] Z Li W Chen and H Hao ldquoNumerical study of sandwichpanel with a new bi-directional load-self-cancelling (LSC)core under blast loadingrdquo =in-Walled Structures vol 127pp 90ndash101 2018

[11] K Katsuyama H Kiyokawa and K Sassa ldquoControl thegrowth of cracks from a borehole by a new method of smoothblastingrdquo Mining Safety vol 29 pp 16ndash23 1983

[12] W L Fourney D B Barker and D C Holloway ldquoModelstudies of explosive well stimulation techniquesrdquo In-ternational Journal of Rock Mechanics and Mining Sciences ampGeomechanics Abstracts vol 18 no 2 pp 113ndash127 1981

[13] W L Fourney D B Barker and D C Holloway ldquoModelstudies of well stimulation using propellant chargesrdquo

International Journal of Rock Mechanics and Mining Sciencesamp Geomechanics Abstracts vol 20 no 2 pp 91ndash101 1983

[14] B Mohanty ldquoExplosive generated fractures in rock and rocklike materialsrdquo Engineering Fracture Mechanics vol 35 no 4-5 pp 889ndash898 1990

[15] B Mohanty ldquoFracture-plane control blasts with satelliteholesrdquo in Proceedings of 3rd International Symposium on RockFragmentation by Blasting pp 407ndash418 Australasian Instituteof Mining and Metallurgy Parkville Australia August 1990

[16] Y G Du Z C Zhang and T L Li ldquoStudies on mechanicaleffect produced by the V-shaped notch borehole blastingrdquoExplosion and Shock Waves vol 11 pp 26ndash30 1991

[17] Q Zong ldquoeoretical study on the cracking mechanism ofnotched borehole blastingrdquo Coal Mine Blasting vol 1pp 12ndash16 1995

[18] Q Zong ldquoInvestigations into mechanism of crack formationfor grooved hole-well blastingrdquo Chinese Journal of Geo-technical Engineering vol 20 no 1 pp 30ndash33 1998

[19] S H Cho Y Nakamura and K Kaneko ldquoDynamic fractureprocess analysis of rock subjected to a stress wave and gaspressurizationrdquo International Journal of Rock Mechanics andMining Sciences vol 41 no 3 pp 433ndash440 2004

[20] Y Zhang ldquoDynamic numerical simulation for the mechanismof V-shaped notch blastingrdquo Explosive Materials vol 38no 4 pp 1ndash5 2009

[21] R S Yang and Y B Wang ldquoDynamic caustic experiment onfracture behaviors of flawed material induced by pre-notchedblastingrdquo Explosive and Shock Waves vol 36 no 2pp 145ndash152 2016

[22] R S Yang C X Ding L Y Yang P Xu and C Chen ldquoHoledefects affect the dynamic fracture behavior of nearby runningcracksrdquo Shock and Vibration vol 2018 Article ID 58943568 pages 2018

[23] Z W Yue Y Guo X Wang et al ldquoInfluence of empty holeshape on directional fracture controlled blasting of rockrdquoRock and Soil Mechanics vol 37 no 2 pp 376ndash382 2016

[24] Z Yue P Qiu R Yang S Zhang K Yuan and Z Li ldquoStressanalysis of the interaction of a running crack and blastingwaves by caustics methodrdquo Engineering Fracture Mechanicsvol 184 pp 339ndash351 2017

[25] B Chen C Liu and J X Yang ldquoAnalysis and application oncontrolling thick hard roof caving with deep-hole positionpresplitting blastingrdquoAdvances in Civil Engineering vol 2018Article ID 9763137 15 pages 2018

[26] Y H Zhu and X P Xu ldquoDamage control characteristics fornotched blasting based on the damage mechanismrdquo Journal ofChina Coal Society vol 42 no 2 pp 369ndash376 2017

[27] X H Li L Yang J S Wang et al ldquoe natural frequencycharacteristic of the self-excited oscillation pulsed water jetdevicerdquo Journal of China Coal Society vol 25 no 6pp 641ndash644 2000

[28] X H Li Y Y Lu Y Zhao et al ldquoStudy on improving thepermeability of soft coal seam with high pressure pulsed waterjetrdquo Journal of China Coal Society vol 33 no 12 pp 1386ndash1390 2007

[29] Y Kang X C Wang X F Yang et al ldquoNumerical simulationof control blasting with borehole protecting and water jetslotting in soft rock massrdquo Disaster Advances vol 5 no 4pp 933ndash938 2012

[30] J-G Kim and J-J Song ldquoAbrasive water jet cutting methodsfor reducing blast-induced ground vibration in tunnel ex-cavationrdquo International Journal of Rock Mechanics andMining Sciences vol 75 pp 147ndash158 2015

14 Shock and Vibration

[31] Y Kang D D Zheng D F Su et al ldquoModel of directionalshaped blasting assisted with water jet and its numericalsimulationrdquo Journal of Vibration and Shock vol 34pp 182ndash188 2015

[32] D Su Y Kang F Yan D Zheng X Wang and M WeildquoCrack propagation law affected by natural fracture and waterjet slot under blast loadingrdquo Combustion Explosion andShock Waves vol 54 no 6 pp 747ndash756 2018

[33] Y B Wang ldquoRock dynamic fracture characteristics based onNSCB impact methodrdquo Shock and Vibration vol 2018 Ar-ticle ID 3105384 13 pages 2018

[34] J Dai Dynamic Behaviors and Blasting =eory of RockMetallurgical Industry Press Beijing China 2013

[35] LSTC LS-DYNAKeyword Userrsquos Manual Livermore SoftwareTechnology Corporation Livermore CA USA 2007

Shock and Vibration 15

International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

RoboticsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Active and Passive Electronic Components

VLSI Design

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Shock and Vibration

Hindawiwwwhindawicom Volume 2018

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom

Journal ofEngineeringVolume 2018

SensorsJournal of

Hindawiwwwhindawicom Volume 2018

International Journal of

RotatingMachinery

Hindawiwwwhindawicom Volume 2018

Modelling ampSimulationin EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Navigation and Observation

International Journal of

Hindawi

wwwhindawicom Volume 2018

Advances in

Multimedia

Submit your manuscripts atwwwhindawicom

Page 11: ExperimentalStudyandNumericalSimulationofDynamic Stress ...downloads.hindawi.com/journals/sv/2019/1659175.pdf,kLL jLL xLL L xLL jLL,kLL L L©L, L©Lk L©Lff L©Lx _NF ig E NFE #_#YNIkff©,Ifiig

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(a)

ndash100

ndash50

0

50

100

150

0000 0001 0002 0003 0004Pres

sure

(MPa

)

Time (s)

Dmrb = 8Dmrb = 12

Dmrb = 16Dmrb = 20

(b)

Figure 15 P-T curve of different monitoring points of 3 simulation case (a) αn 0deg (b) αn 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(b)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(c)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

(d)

Figure 16 Effective stress curve of different monitoring points of 1 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 11

blasting the effective stress of each curve shows the sametrend if Dmrb is certain and the effective stress decreasesgradually and becomes stable with the increase of Dmrb For2 simulation case the peak value of effective stress de-creases with the increase of Dmrb and αn at is to say ifDmrb is certain the rock located at different directionsaround the blasthole suffered different effective stress thecloser the rock gets to the direction of water jet the biggerthe effective stress the rock suffered For 3 simulation casethe variation trend of effective stress is similar to that of 2simulation case but the peak value of each effective stresscurve is quite different By comparing each effective stresscurve of 2 simulation case and 3 simulation case we cansee that in the direction of water jet slot the peak value ofeffective stress of 3 simulation case is always bigger thanthat of 2 simulation case However in the direction per-pendicular to the direction of the jet slot the peak value ofeffective stress of 3 simulation case is always smaller than

that of 2 simulation case which indicates that the existenceof blasthole wall protection material is not only very ben-eficial to the ldquoguiding effectrdquo of blast-induced crack prop-agation by water jet slot but also beneficial to reduce blast-induced damage of remaining rock mass

Moreover by comparing Figures 16(d) 17(d) and 18(d)we can see that in the direction of water jet slot the effectivestress of 2 simulation case decreases gradually and whenDmrb is 20 the distribution-evolution law of effective stressis similar to that of 1 simulation case However for 3simulation case when Dmrb is 20 the peak value of effectivestress is bigger than that of 2 simulation case and thegrowing trend of effective stress shows a large fluctuationwhich suggested that the rock suffered the ldquoguiding effectrdquo bywater jet slot In addition in the other direction of blastholethe distribution-evolution law of effective stress is similar tothat of 1 simulation case at is to say the bigger Dmrb isthe weaker the ldquoguiding effectrdquo and ldquoblasthole wall

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 17 Effective stress curve of different monitoring points of 2 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

12 Shock and Vibration

protection effectrdquo by water jet slot and wall protectionmaterial are

4 Conclusions

In summary some conclusions can be summarized asfollows

e experiment test on dynamic blast strain was con-ducted and the results indicated that under the combinedeffect of blasthole wall protection material and water jet slotthe blasting strain fields were changed by comparing withthe regular blasthole blasting In the direction of water jetslot the PSPV was increased by 8500 and in the directionperpendicular to the direction of water jet slot the PSPV wasreduced by 7021

Numerical simulation results suggest that the existence ofwater jet slot and blasthole wall protection material can affectthe distribution and evolution law of explosive stress waveand let the stress concentration occur at the tip of water jet

slot which promotes blast-induced crack propagation alongthe specific direction and minimizes the blast-induceddamage of remaining rock mass Moreover the bigger Dmrb is the weaker the ldquoguiding effectrdquo and ldquoblasthole wallprotection effectrdquo by water jet slot and wall protection ma-terial are

Both the experiment test result and the numericalsimulation results indicated that the existence of blastholewall protection material is not only beneficial to the ldquoguidingeffectrdquo of blast-induced crack propagation of water jet slotbut also beneficial to reduce blast-induced damage ofremaining rock mass

Future research work will be focused on the applicationsin practical engineering of this approach

Data Availability

Readers can access the data supporting the conclusions ofthe study by sending a mail to the corresponding author

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 18 Effective stress curve of different monitoring points of 3 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 13

(e-mail dengfengcqu163com) and all data can be cosh-ared without restriction

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

Financial support for this work was provided by the NaturalScience Foundation of Southwest University of Science andTechnology (18zx7124) In particular the authors thank ME D Y Li and M E F W Yan for their kind help inexperimental investigation and sincere suggestion

References

[1] Z N Zhao X T Feng Y X Xiao et al ldquoMicroseismiccharacteristics and rockburst risk of deep tunnel constructedby different excavation methodsrdquo Chinese Journal of Geo-technical Engineering vol 38 no 5 pp 0867ndash0876 2016

[2] Z C Zhang ldquoControl in blasting engineeringrdquo ChineseJournal of Underground Space and Engineering vol 9 no 5pp 1208ndash1214 2013

[3] Y Wang ldquoStudy of the dynamic fracture effect using slottedcartridge decoupling charge blastingrdquo International Journal ofRock Mechanics and Mining Sciences vol 96 pp 34ndash46 2017

[4] S S Rathore and S Bhandari ldquoControlled fracture growth byblasting while protecting damages to remaining rockrdquo RockMechanics and Rock Engineering vol 40 no 3 pp 317ndash3262007

[5] S H Cho Y Nakamura B Mohanty H S Yang andK Kaneko ldquoNumerical study of fracture plane control inlaboratory-scale blastingrdquo Engineering Fracture Mechanicsvol 75 no 13 pp 3966ndash3984 2008

[6] R S Yang Y B Wang and L Y Yang ldquoDynamic causticexperimental study of crack propagation in two borehole cutblastingrdquo Journal of China University of Mining amp Technologyvol 41 no 6 pp 868ndash872 2012

[7] WM Liang X L Yang and Y Q Yu ldquoResearch on theory ondirectional fracture controlled blastingrdquo Journal of LiaoningTechnical University vol 25 no 5 pp 702ndash704 2006

[8] J S Song Y B Wang X T Gao et al ldquoe mechanism ofdirectional fracture controlled blasting and its applicationrdquoJournal of Mining Science and Technology vol 1 no 1pp 16ndash28 2016

[9] Y Wang ldquoExperimental research on the influence of anempty-hole defect on crack connections between a direc-tionally fractured blast holerdquo Journal of Testing and Evalu-ation vol 45 no 6 pp 2139ndash2150 2017

[10] Z Li W Chen and H Hao ldquoNumerical study of sandwichpanel with a new bi-directional load-self-cancelling (LSC)core under blast loadingrdquo =in-Walled Structures vol 127pp 90ndash101 2018

[11] K Katsuyama H Kiyokawa and K Sassa ldquoControl thegrowth of cracks from a borehole by a new method of smoothblastingrdquo Mining Safety vol 29 pp 16ndash23 1983

[12] W L Fourney D B Barker and D C Holloway ldquoModelstudies of explosive well stimulation techniquesrdquo In-ternational Journal of Rock Mechanics and Mining Sciences ampGeomechanics Abstracts vol 18 no 2 pp 113ndash127 1981

[13] W L Fourney D B Barker and D C Holloway ldquoModelstudies of well stimulation using propellant chargesrdquo

International Journal of Rock Mechanics and Mining Sciencesamp Geomechanics Abstracts vol 20 no 2 pp 91ndash101 1983

[14] B Mohanty ldquoExplosive generated fractures in rock and rocklike materialsrdquo Engineering Fracture Mechanics vol 35 no 4-5 pp 889ndash898 1990

[15] B Mohanty ldquoFracture-plane control blasts with satelliteholesrdquo in Proceedings of 3rd International Symposium on RockFragmentation by Blasting pp 407ndash418 Australasian Instituteof Mining and Metallurgy Parkville Australia August 1990

[16] Y G Du Z C Zhang and T L Li ldquoStudies on mechanicaleffect produced by the V-shaped notch borehole blastingrdquoExplosion and Shock Waves vol 11 pp 26ndash30 1991

[17] Q Zong ldquoeoretical study on the cracking mechanism ofnotched borehole blastingrdquo Coal Mine Blasting vol 1pp 12ndash16 1995

[18] Q Zong ldquoInvestigations into mechanism of crack formationfor grooved hole-well blastingrdquo Chinese Journal of Geo-technical Engineering vol 20 no 1 pp 30ndash33 1998

[19] S H Cho Y Nakamura and K Kaneko ldquoDynamic fractureprocess analysis of rock subjected to a stress wave and gaspressurizationrdquo International Journal of Rock Mechanics andMining Sciences vol 41 no 3 pp 433ndash440 2004

[20] Y Zhang ldquoDynamic numerical simulation for the mechanismof V-shaped notch blastingrdquo Explosive Materials vol 38no 4 pp 1ndash5 2009

[21] R S Yang and Y B Wang ldquoDynamic caustic experiment onfracture behaviors of flawed material induced by pre-notchedblastingrdquo Explosive and Shock Waves vol 36 no 2pp 145ndash152 2016

[22] R S Yang C X Ding L Y Yang P Xu and C Chen ldquoHoledefects affect the dynamic fracture behavior of nearby runningcracksrdquo Shock and Vibration vol 2018 Article ID 58943568 pages 2018

[23] Z W Yue Y Guo X Wang et al ldquoInfluence of empty holeshape on directional fracture controlled blasting of rockrdquoRock and Soil Mechanics vol 37 no 2 pp 376ndash382 2016

[24] Z Yue P Qiu R Yang S Zhang K Yuan and Z Li ldquoStressanalysis of the interaction of a running crack and blastingwaves by caustics methodrdquo Engineering Fracture Mechanicsvol 184 pp 339ndash351 2017

[25] B Chen C Liu and J X Yang ldquoAnalysis and application oncontrolling thick hard roof caving with deep-hole positionpresplitting blastingrdquoAdvances in Civil Engineering vol 2018Article ID 9763137 15 pages 2018

[26] Y H Zhu and X P Xu ldquoDamage control characteristics fornotched blasting based on the damage mechanismrdquo Journal ofChina Coal Society vol 42 no 2 pp 369ndash376 2017

[27] X H Li L Yang J S Wang et al ldquoe natural frequencycharacteristic of the self-excited oscillation pulsed water jetdevicerdquo Journal of China Coal Society vol 25 no 6pp 641ndash644 2000

[28] X H Li Y Y Lu Y Zhao et al ldquoStudy on improving thepermeability of soft coal seam with high pressure pulsed waterjetrdquo Journal of China Coal Society vol 33 no 12 pp 1386ndash1390 2007

[29] Y Kang X C Wang X F Yang et al ldquoNumerical simulationof control blasting with borehole protecting and water jetslotting in soft rock massrdquo Disaster Advances vol 5 no 4pp 933ndash938 2012

[30] J-G Kim and J-J Song ldquoAbrasive water jet cutting methodsfor reducing blast-induced ground vibration in tunnel ex-cavationrdquo International Journal of Rock Mechanics andMining Sciences vol 75 pp 147ndash158 2015

14 Shock and Vibration

[31] Y Kang D D Zheng D F Su et al ldquoModel of directionalshaped blasting assisted with water jet and its numericalsimulationrdquo Journal of Vibration and Shock vol 34pp 182ndash188 2015

[32] D Su Y Kang F Yan D Zheng X Wang and M WeildquoCrack propagation law affected by natural fracture and waterjet slot under blast loadingrdquo Combustion Explosion andShock Waves vol 54 no 6 pp 747ndash756 2018

[33] Y B Wang ldquoRock dynamic fracture characteristics based onNSCB impact methodrdquo Shock and Vibration vol 2018 Ar-ticle ID 3105384 13 pages 2018

[34] J Dai Dynamic Behaviors and Blasting =eory of RockMetallurgical Industry Press Beijing China 2013

[35] LSTC LS-DYNAKeyword Userrsquos Manual Livermore SoftwareTechnology Corporation Livermore CA USA 2007

Shock and Vibration 15

International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

RoboticsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Active and Passive Electronic Components

VLSI Design

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Shock and Vibration

Hindawiwwwhindawicom Volume 2018

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom

Journal ofEngineeringVolume 2018

SensorsJournal of

Hindawiwwwhindawicom Volume 2018

International Journal of

RotatingMachinery

Hindawiwwwhindawicom Volume 2018

Modelling ampSimulationin EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Navigation and Observation

International Journal of

Hindawi

wwwhindawicom Volume 2018

Advances in

Multimedia

Submit your manuscripts atwwwhindawicom

Page 12: ExperimentalStudyandNumericalSimulationofDynamic Stress ...downloads.hindawi.com/journals/sv/2019/1659175.pdf,kLL jLL xLL L xLL jLL,kLL L L©L, L©Lk L©Lff L©Lx _NF ig E NFE #_#YNIkff©,Ifiig

blasting the effective stress of each curve shows the sametrend if Dmrb is certain and the effective stress decreasesgradually and becomes stable with the increase of Dmrb For2 simulation case the peak value of effective stress de-creases with the increase of Dmrb and αn at is to say ifDmrb is certain the rock located at different directionsaround the blasthole suffered different effective stress thecloser the rock gets to the direction of water jet the biggerthe effective stress the rock suffered For 3 simulation casethe variation trend of effective stress is similar to that of 2simulation case but the peak value of each effective stresscurve is quite different By comparing each effective stresscurve of 2 simulation case and 3 simulation case we cansee that in the direction of water jet slot the peak value ofeffective stress of 3 simulation case is always bigger thanthat of 2 simulation case However in the direction per-pendicular to the direction of the jet slot the peak value ofeffective stress of 3 simulation case is always smaller than

that of 2 simulation case which indicates that the existenceof blasthole wall protection material is not only very ben-eficial to the ldquoguiding effectrdquo of blast-induced crack prop-agation by water jet slot but also beneficial to reduce blast-induced damage of remaining rock mass

Moreover by comparing Figures 16(d) 17(d) and 18(d)we can see that in the direction of water jet slot the effectivestress of 2 simulation case decreases gradually and whenDmrb is 20 the distribution-evolution law of effective stressis similar to that of 1 simulation case However for 3simulation case when Dmrb is 20 the peak value of effectivestress is bigger than that of 2 simulation case and thegrowing trend of effective stress shows a large fluctuationwhich suggested that the rock suffered the ldquoguiding effectrdquo bywater jet slot In addition in the other direction of blastholethe distribution-evolution law of effective stress is similar tothat of 1 simulation case at is to say the bigger Dmrb isthe weaker the ldquoguiding effectrdquo and ldquoblasthole wall

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 17 Effective stress curve of different monitoring points of 2 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

12 Shock and Vibration

protection effectrdquo by water jet slot and wall protectionmaterial are

4 Conclusions

In summary some conclusions can be summarized asfollows

e experiment test on dynamic blast strain was con-ducted and the results indicated that under the combinedeffect of blasthole wall protection material and water jet slotthe blasting strain fields were changed by comparing withthe regular blasthole blasting In the direction of water jetslot the PSPV was increased by 8500 and in the directionperpendicular to the direction of water jet slot the PSPV wasreduced by 7021

Numerical simulation results suggest that the existence ofwater jet slot and blasthole wall protection material can affectthe distribution and evolution law of explosive stress waveand let the stress concentration occur at the tip of water jet

slot which promotes blast-induced crack propagation alongthe specific direction and minimizes the blast-induceddamage of remaining rock mass Moreover the bigger Dmrb is the weaker the ldquoguiding effectrdquo and ldquoblasthole wallprotection effectrdquo by water jet slot and wall protection ma-terial are

Both the experiment test result and the numericalsimulation results indicated that the existence of blastholewall protection material is not only beneficial to the ldquoguidingeffectrdquo of blast-induced crack propagation of water jet slotbut also beneficial to reduce blast-induced damage ofremaining rock mass

Future research work will be focused on the applicationsin practical engineering of this approach

Data Availability

Readers can access the data supporting the conclusions ofthe study by sending a mail to the corresponding author

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 18 Effective stress curve of different monitoring points of 3 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 13

(e-mail dengfengcqu163com) and all data can be cosh-ared without restriction

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

Financial support for this work was provided by the NaturalScience Foundation of Southwest University of Science andTechnology (18zx7124) In particular the authors thank ME D Y Li and M E F W Yan for their kind help inexperimental investigation and sincere suggestion

References

[1] Z N Zhao X T Feng Y X Xiao et al ldquoMicroseismiccharacteristics and rockburst risk of deep tunnel constructedby different excavation methodsrdquo Chinese Journal of Geo-technical Engineering vol 38 no 5 pp 0867ndash0876 2016

[2] Z C Zhang ldquoControl in blasting engineeringrdquo ChineseJournal of Underground Space and Engineering vol 9 no 5pp 1208ndash1214 2013

[3] Y Wang ldquoStudy of the dynamic fracture effect using slottedcartridge decoupling charge blastingrdquo International Journal ofRock Mechanics and Mining Sciences vol 96 pp 34ndash46 2017

[4] S S Rathore and S Bhandari ldquoControlled fracture growth byblasting while protecting damages to remaining rockrdquo RockMechanics and Rock Engineering vol 40 no 3 pp 317ndash3262007

[5] S H Cho Y Nakamura B Mohanty H S Yang andK Kaneko ldquoNumerical study of fracture plane control inlaboratory-scale blastingrdquo Engineering Fracture Mechanicsvol 75 no 13 pp 3966ndash3984 2008

[6] R S Yang Y B Wang and L Y Yang ldquoDynamic causticexperimental study of crack propagation in two borehole cutblastingrdquo Journal of China University of Mining amp Technologyvol 41 no 6 pp 868ndash872 2012

[7] WM Liang X L Yang and Y Q Yu ldquoResearch on theory ondirectional fracture controlled blastingrdquo Journal of LiaoningTechnical University vol 25 no 5 pp 702ndash704 2006

[8] J S Song Y B Wang X T Gao et al ldquoe mechanism ofdirectional fracture controlled blasting and its applicationrdquoJournal of Mining Science and Technology vol 1 no 1pp 16ndash28 2016

[9] Y Wang ldquoExperimental research on the influence of anempty-hole defect on crack connections between a direc-tionally fractured blast holerdquo Journal of Testing and Evalu-ation vol 45 no 6 pp 2139ndash2150 2017

[10] Z Li W Chen and H Hao ldquoNumerical study of sandwichpanel with a new bi-directional load-self-cancelling (LSC)core under blast loadingrdquo =in-Walled Structures vol 127pp 90ndash101 2018

[11] K Katsuyama H Kiyokawa and K Sassa ldquoControl thegrowth of cracks from a borehole by a new method of smoothblastingrdquo Mining Safety vol 29 pp 16ndash23 1983

[12] W L Fourney D B Barker and D C Holloway ldquoModelstudies of explosive well stimulation techniquesrdquo In-ternational Journal of Rock Mechanics and Mining Sciences ampGeomechanics Abstracts vol 18 no 2 pp 113ndash127 1981

[13] W L Fourney D B Barker and D C Holloway ldquoModelstudies of well stimulation using propellant chargesrdquo

International Journal of Rock Mechanics and Mining Sciencesamp Geomechanics Abstracts vol 20 no 2 pp 91ndash101 1983

[14] B Mohanty ldquoExplosive generated fractures in rock and rocklike materialsrdquo Engineering Fracture Mechanics vol 35 no 4-5 pp 889ndash898 1990

[15] B Mohanty ldquoFracture-plane control blasts with satelliteholesrdquo in Proceedings of 3rd International Symposium on RockFragmentation by Blasting pp 407ndash418 Australasian Instituteof Mining and Metallurgy Parkville Australia August 1990

[16] Y G Du Z C Zhang and T L Li ldquoStudies on mechanicaleffect produced by the V-shaped notch borehole blastingrdquoExplosion and Shock Waves vol 11 pp 26ndash30 1991

[17] Q Zong ldquoeoretical study on the cracking mechanism ofnotched borehole blastingrdquo Coal Mine Blasting vol 1pp 12ndash16 1995

[18] Q Zong ldquoInvestigations into mechanism of crack formationfor grooved hole-well blastingrdquo Chinese Journal of Geo-technical Engineering vol 20 no 1 pp 30ndash33 1998

[19] S H Cho Y Nakamura and K Kaneko ldquoDynamic fractureprocess analysis of rock subjected to a stress wave and gaspressurizationrdquo International Journal of Rock Mechanics andMining Sciences vol 41 no 3 pp 433ndash440 2004

[20] Y Zhang ldquoDynamic numerical simulation for the mechanismof V-shaped notch blastingrdquo Explosive Materials vol 38no 4 pp 1ndash5 2009

[21] R S Yang and Y B Wang ldquoDynamic caustic experiment onfracture behaviors of flawed material induced by pre-notchedblastingrdquo Explosive and Shock Waves vol 36 no 2pp 145ndash152 2016

[22] R S Yang C X Ding L Y Yang P Xu and C Chen ldquoHoledefects affect the dynamic fracture behavior of nearby runningcracksrdquo Shock and Vibration vol 2018 Article ID 58943568 pages 2018

[23] Z W Yue Y Guo X Wang et al ldquoInfluence of empty holeshape on directional fracture controlled blasting of rockrdquoRock and Soil Mechanics vol 37 no 2 pp 376ndash382 2016

[24] Z Yue P Qiu R Yang S Zhang K Yuan and Z Li ldquoStressanalysis of the interaction of a running crack and blastingwaves by caustics methodrdquo Engineering Fracture Mechanicsvol 184 pp 339ndash351 2017

[25] B Chen C Liu and J X Yang ldquoAnalysis and application oncontrolling thick hard roof caving with deep-hole positionpresplitting blastingrdquoAdvances in Civil Engineering vol 2018Article ID 9763137 15 pages 2018

[26] Y H Zhu and X P Xu ldquoDamage control characteristics fornotched blasting based on the damage mechanismrdquo Journal ofChina Coal Society vol 42 no 2 pp 369ndash376 2017

[27] X H Li L Yang J S Wang et al ldquoe natural frequencycharacteristic of the self-excited oscillation pulsed water jetdevicerdquo Journal of China Coal Society vol 25 no 6pp 641ndash644 2000

[28] X H Li Y Y Lu Y Zhao et al ldquoStudy on improving thepermeability of soft coal seam with high pressure pulsed waterjetrdquo Journal of China Coal Society vol 33 no 12 pp 1386ndash1390 2007

[29] Y Kang X C Wang X F Yang et al ldquoNumerical simulationof control blasting with borehole protecting and water jetslotting in soft rock massrdquo Disaster Advances vol 5 no 4pp 933ndash938 2012

[30] J-G Kim and J-J Song ldquoAbrasive water jet cutting methodsfor reducing blast-induced ground vibration in tunnel ex-cavationrdquo International Journal of Rock Mechanics andMining Sciences vol 75 pp 147ndash158 2015

14 Shock and Vibration

[31] Y Kang D D Zheng D F Su et al ldquoModel of directionalshaped blasting assisted with water jet and its numericalsimulationrdquo Journal of Vibration and Shock vol 34pp 182ndash188 2015

[32] D Su Y Kang F Yan D Zheng X Wang and M WeildquoCrack propagation law affected by natural fracture and waterjet slot under blast loadingrdquo Combustion Explosion andShock Waves vol 54 no 6 pp 747ndash756 2018

[33] Y B Wang ldquoRock dynamic fracture characteristics based onNSCB impact methodrdquo Shock and Vibration vol 2018 Ar-ticle ID 3105384 13 pages 2018

[34] J Dai Dynamic Behaviors and Blasting =eory of RockMetallurgical Industry Press Beijing China 2013

[35] LSTC LS-DYNAKeyword Userrsquos Manual Livermore SoftwareTechnology Corporation Livermore CA USA 2007

Shock and Vibration 15

International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

RoboticsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Active and Passive Electronic Components

VLSI Design

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Shock and Vibration

Hindawiwwwhindawicom Volume 2018

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom

Journal ofEngineeringVolume 2018

SensorsJournal of

Hindawiwwwhindawicom Volume 2018

International Journal of

RotatingMachinery

Hindawiwwwhindawicom Volume 2018

Modelling ampSimulationin EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Navigation and Observation

International Journal of

Hindawi

wwwhindawicom Volume 2018

Advances in

Multimedia

Submit your manuscripts atwwwhindawicom

Page 13: ExperimentalStudyandNumericalSimulationofDynamic Stress ...downloads.hindawi.com/journals/sv/2019/1659175.pdf,kLL jLL xLL L xLL jLL,kLL L L©L, L©Lk L©Lff L©Lx _NF ig E NFE #_#YNIkff©,Ifiig

protection effectrdquo by water jet slot and wall protectionmaterial are

4 Conclusions

In summary some conclusions can be summarized asfollows

e experiment test on dynamic blast strain was con-ducted and the results indicated that under the combinedeffect of blasthole wall protection material and water jet slotthe blasting strain fields were changed by comparing withthe regular blasthole blasting In the direction of water jetslot the PSPV was increased by 8500 and in the directionperpendicular to the direction of water jet slot the PSPV wasreduced by 7021

Numerical simulation results suggest that the existence ofwater jet slot and blasthole wall protection material can affectthe distribution and evolution law of explosive stress waveand let the stress concentration occur at the tip of water jet

slot which promotes blast-induced crack propagation alongthe specific direction and minimizes the blast-induceddamage of remaining rock mass Moreover the bigger Dmrb is the weaker the ldquoguiding effectrdquo and ldquoblasthole wallprotection effectrdquo by water jet slot and wall protection ma-terial are

Both the experiment test result and the numericalsimulation results indicated that the existence of blastholewall protection material is not only beneficial to the ldquoguidingeffectrdquo of blast-induced crack propagation of water jet slotbut also beneficial to reduce blast-induced damage ofremaining rock mass

Future research work will be focused on the applicationsin practical engineering of this approach

Data Availability

Readers can access the data supporting the conclusions ofthe study by sending a mail to the corresponding author

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(a)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(b)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(c)

0

20

40

60

80

100

0000 0001 0002 0003 0004

Effe

ctiv

e str

ess (

MPa

)

Time (s)

αn = 0degαn = 30deg

αn = 60degαn = 90deg

(d)

Figure 18 Effective stress curve of different monitoring points of 3 simulation case (a) Dmrb 8 (b) Dmrb 12 (c) Dmrb 16 (d) Dmrb 20

Shock and Vibration 13

(e-mail dengfengcqu163com) and all data can be cosh-ared without restriction

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

Financial support for this work was provided by the NaturalScience Foundation of Southwest University of Science andTechnology (18zx7124) In particular the authors thank ME D Y Li and M E F W Yan for their kind help inexperimental investigation and sincere suggestion

References

[1] Z N Zhao X T Feng Y X Xiao et al ldquoMicroseismiccharacteristics and rockburst risk of deep tunnel constructedby different excavation methodsrdquo Chinese Journal of Geo-technical Engineering vol 38 no 5 pp 0867ndash0876 2016

[2] Z C Zhang ldquoControl in blasting engineeringrdquo ChineseJournal of Underground Space and Engineering vol 9 no 5pp 1208ndash1214 2013

[3] Y Wang ldquoStudy of the dynamic fracture effect using slottedcartridge decoupling charge blastingrdquo International Journal ofRock Mechanics and Mining Sciences vol 96 pp 34ndash46 2017

[4] S S Rathore and S Bhandari ldquoControlled fracture growth byblasting while protecting damages to remaining rockrdquo RockMechanics and Rock Engineering vol 40 no 3 pp 317ndash3262007

[5] S H Cho Y Nakamura B Mohanty H S Yang andK Kaneko ldquoNumerical study of fracture plane control inlaboratory-scale blastingrdquo Engineering Fracture Mechanicsvol 75 no 13 pp 3966ndash3984 2008

[6] R S Yang Y B Wang and L Y Yang ldquoDynamic causticexperimental study of crack propagation in two borehole cutblastingrdquo Journal of China University of Mining amp Technologyvol 41 no 6 pp 868ndash872 2012

[7] WM Liang X L Yang and Y Q Yu ldquoResearch on theory ondirectional fracture controlled blastingrdquo Journal of LiaoningTechnical University vol 25 no 5 pp 702ndash704 2006

[8] J S Song Y B Wang X T Gao et al ldquoe mechanism ofdirectional fracture controlled blasting and its applicationrdquoJournal of Mining Science and Technology vol 1 no 1pp 16ndash28 2016

[9] Y Wang ldquoExperimental research on the influence of anempty-hole defect on crack connections between a direc-tionally fractured blast holerdquo Journal of Testing and Evalu-ation vol 45 no 6 pp 2139ndash2150 2017

[10] Z Li W Chen and H Hao ldquoNumerical study of sandwichpanel with a new bi-directional load-self-cancelling (LSC)core under blast loadingrdquo =in-Walled Structures vol 127pp 90ndash101 2018

[11] K Katsuyama H Kiyokawa and K Sassa ldquoControl thegrowth of cracks from a borehole by a new method of smoothblastingrdquo Mining Safety vol 29 pp 16ndash23 1983

[12] W L Fourney D B Barker and D C Holloway ldquoModelstudies of explosive well stimulation techniquesrdquo In-ternational Journal of Rock Mechanics and Mining Sciences ampGeomechanics Abstracts vol 18 no 2 pp 113ndash127 1981

[13] W L Fourney D B Barker and D C Holloway ldquoModelstudies of well stimulation using propellant chargesrdquo

International Journal of Rock Mechanics and Mining Sciencesamp Geomechanics Abstracts vol 20 no 2 pp 91ndash101 1983

[14] B Mohanty ldquoExplosive generated fractures in rock and rocklike materialsrdquo Engineering Fracture Mechanics vol 35 no 4-5 pp 889ndash898 1990

[15] B Mohanty ldquoFracture-plane control blasts with satelliteholesrdquo in Proceedings of 3rd International Symposium on RockFragmentation by Blasting pp 407ndash418 Australasian Instituteof Mining and Metallurgy Parkville Australia August 1990

[16] Y G Du Z C Zhang and T L Li ldquoStudies on mechanicaleffect produced by the V-shaped notch borehole blastingrdquoExplosion and Shock Waves vol 11 pp 26ndash30 1991

[17] Q Zong ldquoeoretical study on the cracking mechanism ofnotched borehole blastingrdquo Coal Mine Blasting vol 1pp 12ndash16 1995

[18] Q Zong ldquoInvestigations into mechanism of crack formationfor grooved hole-well blastingrdquo Chinese Journal of Geo-technical Engineering vol 20 no 1 pp 30ndash33 1998

[19] S H Cho Y Nakamura and K Kaneko ldquoDynamic fractureprocess analysis of rock subjected to a stress wave and gaspressurizationrdquo International Journal of Rock Mechanics andMining Sciences vol 41 no 3 pp 433ndash440 2004

[20] Y Zhang ldquoDynamic numerical simulation for the mechanismof V-shaped notch blastingrdquo Explosive Materials vol 38no 4 pp 1ndash5 2009

[21] R S Yang and Y B Wang ldquoDynamic caustic experiment onfracture behaviors of flawed material induced by pre-notchedblastingrdquo Explosive and Shock Waves vol 36 no 2pp 145ndash152 2016

[22] R S Yang C X Ding L Y Yang P Xu and C Chen ldquoHoledefects affect the dynamic fracture behavior of nearby runningcracksrdquo Shock and Vibration vol 2018 Article ID 58943568 pages 2018

[23] Z W Yue Y Guo X Wang et al ldquoInfluence of empty holeshape on directional fracture controlled blasting of rockrdquoRock and Soil Mechanics vol 37 no 2 pp 376ndash382 2016

[24] Z Yue P Qiu R Yang S Zhang K Yuan and Z Li ldquoStressanalysis of the interaction of a running crack and blastingwaves by caustics methodrdquo Engineering Fracture Mechanicsvol 184 pp 339ndash351 2017

[25] B Chen C Liu and J X Yang ldquoAnalysis and application oncontrolling thick hard roof caving with deep-hole positionpresplitting blastingrdquoAdvances in Civil Engineering vol 2018Article ID 9763137 15 pages 2018

[26] Y H Zhu and X P Xu ldquoDamage control characteristics fornotched blasting based on the damage mechanismrdquo Journal ofChina Coal Society vol 42 no 2 pp 369ndash376 2017

[27] X H Li L Yang J S Wang et al ldquoe natural frequencycharacteristic of the self-excited oscillation pulsed water jetdevicerdquo Journal of China Coal Society vol 25 no 6pp 641ndash644 2000

[28] X H Li Y Y Lu Y Zhao et al ldquoStudy on improving thepermeability of soft coal seam with high pressure pulsed waterjetrdquo Journal of China Coal Society vol 33 no 12 pp 1386ndash1390 2007

[29] Y Kang X C Wang X F Yang et al ldquoNumerical simulationof control blasting with borehole protecting and water jetslotting in soft rock massrdquo Disaster Advances vol 5 no 4pp 933ndash938 2012

[30] J-G Kim and J-J Song ldquoAbrasive water jet cutting methodsfor reducing blast-induced ground vibration in tunnel ex-cavationrdquo International Journal of Rock Mechanics andMining Sciences vol 75 pp 147ndash158 2015

14 Shock and Vibration

[31] Y Kang D D Zheng D F Su et al ldquoModel of directionalshaped blasting assisted with water jet and its numericalsimulationrdquo Journal of Vibration and Shock vol 34pp 182ndash188 2015

[32] D Su Y Kang F Yan D Zheng X Wang and M WeildquoCrack propagation law affected by natural fracture and waterjet slot under blast loadingrdquo Combustion Explosion andShock Waves vol 54 no 6 pp 747ndash756 2018

[33] Y B Wang ldquoRock dynamic fracture characteristics based onNSCB impact methodrdquo Shock and Vibration vol 2018 Ar-ticle ID 3105384 13 pages 2018

[34] J Dai Dynamic Behaviors and Blasting =eory of RockMetallurgical Industry Press Beijing China 2013

[35] LSTC LS-DYNAKeyword Userrsquos Manual Livermore SoftwareTechnology Corporation Livermore CA USA 2007

Shock and Vibration 15

International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

RoboticsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Active and Passive Electronic Components

VLSI Design

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Shock and Vibration

Hindawiwwwhindawicom Volume 2018

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom

Journal ofEngineeringVolume 2018

SensorsJournal of

Hindawiwwwhindawicom Volume 2018

International Journal of

RotatingMachinery

Hindawiwwwhindawicom Volume 2018

Modelling ampSimulationin EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Navigation and Observation

International Journal of

Hindawi

wwwhindawicom Volume 2018

Advances in

Multimedia

Submit your manuscripts atwwwhindawicom

Page 14: ExperimentalStudyandNumericalSimulationofDynamic Stress ...downloads.hindawi.com/journals/sv/2019/1659175.pdf,kLL jLL xLL L xLL jLL,kLL L L©L, L©Lk L©Lff L©Lx _NF ig E NFE #_#YNIkff©,Ifiig

(e-mail dengfengcqu163com) and all data can be cosh-ared without restriction

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

Financial support for this work was provided by the NaturalScience Foundation of Southwest University of Science andTechnology (18zx7124) In particular the authors thank ME D Y Li and M E F W Yan for their kind help inexperimental investigation and sincere suggestion

References

[1] Z N Zhao X T Feng Y X Xiao et al ldquoMicroseismiccharacteristics and rockburst risk of deep tunnel constructedby different excavation methodsrdquo Chinese Journal of Geo-technical Engineering vol 38 no 5 pp 0867ndash0876 2016

[2] Z C Zhang ldquoControl in blasting engineeringrdquo ChineseJournal of Underground Space and Engineering vol 9 no 5pp 1208ndash1214 2013

[3] Y Wang ldquoStudy of the dynamic fracture effect using slottedcartridge decoupling charge blastingrdquo International Journal ofRock Mechanics and Mining Sciences vol 96 pp 34ndash46 2017

[4] S S Rathore and S Bhandari ldquoControlled fracture growth byblasting while protecting damages to remaining rockrdquo RockMechanics and Rock Engineering vol 40 no 3 pp 317ndash3262007

[5] S H Cho Y Nakamura B Mohanty H S Yang andK Kaneko ldquoNumerical study of fracture plane control inlaboratory-scale blastingrdquo Engineering Fracture Mechanicsvol 75 no 13 pp 3966ndash3984 2008

[6] R S Yang Y B Wang and L Y Yang ldquoDynamic causticexperimental study of crack propagation in two borehole cutblastingrdquo Journal of China University of Mining amp Technologyvol 41 no 6 pp 868ndash872 2012

[7] WM Liang X L Yang and Y Q Yu ldquoResearch on theory ondirectional fracture controlled blastingrdquo Journal of LiaoningTechnical University vol 25 no 5 pp 702ndash704 2006

[8] J S Song Y B Wang X T Gao et al ldquoe mechanism ofdirectional fracture controlled blasting and its applicationrdquoJournal of Mining Science and Technology vol 1 no 1pp 16ndash28 2016

[9] Y Wang ldquoExperimental research on the influence of anempty-hole defect on crack connections between a direc-tionally fractured blast holerdquo Journal of Testing and Evalu-ation vol 45 no 6 pp 2139ndash2150 2017

[10] Z Li W Chen and H Hao ldquoNumerical study of sandwichpanel with a new bi-directional load-self-cancelling (LSC)core under blast loadingrdquo =in-Walled Structures vol 127pp 90ndash101 2018

[11] K Katsuyama H Kiyokawa and K Sassa ldquoControl thegrowth of cracks from a borehole by a new method of smoothblastingrdquo Mining Safety vol 29 pp 16ndash23 1983

[12] W L Fourney D B Barker and D C Holloway ldquoModelstudies of explosive well stimulation techniquesrdquo In-ternational Journal of Rock Mechanics and Mining Sciences ampGeomechanics Abstracts vol 18 no 2 pp 113ndash127 1981

[13] W L Fourney D B Barker and D C Holloway ldquoModelstudies of well stimulation using propellant chargesrdquo

International Journal of Rock Mechanics and Mining Sciencesamp Geomechanics Abstracts vol 20 no 2 pp 91ndash101 1983

[14] B Mohanty ldquoExplosive generated fractures in rock and rocklike materialsrdquo Engineering Fracture Mechanics vol 35 no 4-5 pp 889ndash898 1990

[15] B Mohanty ldquoFracture-plane control blasts with satelliteholesrdquo in Proceedings of 3rd International Symposium on RockFragmentation by Blasting pp 407ndash418 Australasian Instituteof Mining and Metallurgy Parkville Australia August 1990

[16] Y G Du Z C Zhang and T L Li ldquoStudies on mechanicaleffect produced by the V-shaped notch borehole blastingrdquoExplosion and Shock Waves vol 11 pp 26ndash30 1991

[17] Q Zong ldquoeoretical study on the cracking mechanism ofnotched borehole blastingrdquo Coal Mine Blasting vol 1pp 12ndash16 1995

[18] Q Zong ldquoInvestigations into mechanism of crack formationfor grooved hole-well blastingrdquo Chinese Journal of Geo-technical Engineering vol 20 no 1 pp 30ndash33 1998

[19] S H Cho Y Nakamura and K Kaneko ldquoDynamic fractureprocess analysis of rock subjected to a stress wave and gaspressurizationrdquo International Journal of Rock Mechanics andMining Sciences vol 41 no 3 pp 433ndash440 2004

[20] Y Zhang ldquoDynamic numerical simulation for the mechanismof V-shaped notch blastingrdquo Explosive Materials vol 38no 4 pp 1ndash5 2009

[21] R S Yang and Y B Wang ldquoDynamic caustic experiment onfracture behaviors of flawed material induced by pre-notchedblastingrdquo Explosive and Shock Waves vol 36 no 2pp 145ndash152 2016

[22] R S Yang C X Ding L Y Yang P Xu and C Chen ldquoHoledefects affect the dynamic fracture behavior of nearby runningcracksrdquo Shock and Vibration vol 2018 Article ID 58943568 pages 2018

[23] Z W Yue Y Guo X Wang et al ldquoInfluence of empty holeshape on directional fracture controlled blasting of rockrdquoRock and Soil Mechanics vol 37 no 2 pp 376ndash382 2016

[24] Z Yue P Qiu R Yang S Zhang K Yuan and Z Li ldquoStressanalysis of the interaction of a running crack and blastingwaves by caustics methodrdquo Engineering Fracture Mechanicsvol 184 pp 339ndash351 2017

[25] B Chen C Liu and J X Yang ldquoAnalysis and application oncontrolling thick hard roof caving with deep-hole positionpresplitting blastingrdquoAdvances in Civil Engineering vol 2018Article ID 9763137 15 pages 2018

[26] Y H Zhu and X P Xu ldquoDamage control characteristics fornotched blasting based on the damage mechanismrdquo Journal ofChina Coal Society vol 42 no 2 pp 369ndash376 2017

[27] X H Li L Yang J S Wang et al ldquoe natural frequencycharacteristic of the self-excited oscillation pulsed water jetdevicerdquo Journal of China Coal Society vol 25 no 6pp 641ndash644 2000

[28] X H Li Y Y Lu Y Zhao et al ldquoStudy on improving thepermeability of soft coal seam with high pressure pulsed waterjetrdquo Journal of China Coal Society vol 33 no 12 pp 1386ndash1390 2007

[29] Y Kang X C Wang X F Yang et al ldquoNumerical simulationof control blasting with borehole protecting and water jetslotting in soft rock massrdquo Disaster Advances vol 5 no 4pp 933ndash938 2012

[30] J-G Kim and J-J Song ldquoAbrasive water jet cutting methodsfor reducing blast-induced ground vibration in tunnel ex-cavationrdquo International Journal of Rock Mechanics andMining Sciences vol 75 pp 147ndash158 2015

14 Shock and Vibration

[31] Y Kang D D Zheng D F Su et al ldquoModel of directionalshaped blasting assisted with water jet and its numericalsimulationrdquo Journal of Vibration and Shock vol 34pp 182ndash188 2015

[32] D Su Y Kang F Yan D Zheng X Wang and M WeildquoCrack propagation law affected by natural fracture and waterjet slot under blast loadingrdquo Combustion Explosion andShock Waves vol 54 no 6 pp 747ndash756 2018

[33] Y B Wang ldquoRock dynamic fracture characteristics based onNSCB impact methodrdquo Shock and Vibration vol 2018 Ar-ticle ID 3105384 13 pages 2018

[34] J Dai Dynamic Behaviors and Blasting =eory of RockMetallurgical Industry Press Beijing China 2013

[35] LSTC LS-DYNAKeyword Userrsquos Manual Livermore SoftwareTechnology Corporation Livermore CA USA 2007

Shock and Vibration 15

International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

RoboticsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Active and Passive Electronic Components

VLSI Design

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Shock and Vibration

Hindawiwwwhindawicom Volume 2018

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom

Journal ofEngineeringVolume 2018

SensorsJournal of

Hindawiwwwhindawicom Volume 2018

International Journal of

RotatingMachinery

Hindawiwwwhindawicom Volume 2018

Modelling ampSimulationin EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Navigation and Observation

International Journal of

Hindawi

wwwhindawicom Volume 2018

Advances in

Multimedia

Submit your manuscripts atwwwhindawicom

Page 15: ExperimentalStudyandNumericalSimulationofDynamic Stress ...downloads.hindawi.com/journals/sv/2019/1659175.pdf,kLL jLL xLL L xLL jLL,kLL L L©L, L©Lk L©Lff L©Lx _NF ig E NFE #_#YNIkff©,Ifiig

[31] Y Kang D D Zheng D F Su et al ldquoModel of directionalshaped blasting assisted with water jet and its numericalsimulationrdquo Journal of Vibration and Shock vol 34pp 182ndash188 2015

[32] D Su Y Kang F Yan D Zheng X Wang and M WeildquoCrack propagation law affected by natural fracture and waterjet slot under blast loadingrdquo Combustion Explosion andShock Waves vol 54 no 6 pp 747ndash756 2018

[33] Y B Wang ldquoRock dynamic fracture characteristics based onNSCB impact methodrdquo Shock and Vibration vol 2018 Ar-ticle ID 3105384 13 pages 2018

[34] J Dai Dynamic Behaviors and Blasting =eory of RockMetallurgical Industry Press Beijing China 2013

[35] LSTC LS-DYNAKeyword Userrsquos Manual Livermore SoftwareTechnology Corporation Livermore CA USA 2007

Shock and Vibration 15

International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

RoboticsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Active and Passive Electronic Components

VLSI Design

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Shock and Vibration

Hindawiwwwhindawicom Volume 2018

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom

Journal ofEngineeringVolume 2018

SensorsJournal of

Hindawiwwwhindawicom Volume 2018

International Journal of

RotatingMachinery

Hindawiwwwhindawicom Volume 2018

Modelling ampSimulationin EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Navigation and Observation

International Journal of

Hindawi

wwwhindawicom Volume 2018

Advances in

Multimedia

Submit your manuscripts atwwwhindawicom

Page 16: ExperimentalStudyandNumericalSimulationofDynamic Stress ...downloads.hindawi.com/journals/sv/2019/1659175.pdf,kLL jLL xLL L xLL jLL,kLL L L©L, L©Lk L©Lff L©Lx _NF ig E NFE #_#YNIkff©,Ifiig

International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

RoboticsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Active and Passive Electronic Components

VLSI Design

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Shock and Vibration

Hindawiwwwhindawicom Volume 2018

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of

Hindawiwwwhindawicom Volume 2018

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