11/16/2013
1
TAC –Rock Tunnelling Workshop
Vancouver, BC
November 16, 2013
By: Gordon Revey
OVERVIEW OF TUNNEL AND SHAFT BLASTING TECHNOLOGY
SCOPE• Blasting versus Mechanical Methods
• Managing Risk
• Identifying and Controlling Blast Effects
• Case Histories Demonstrating Controlled Blasting Techniques
Drill - BlastDrill - Blast
MechanicalMechanical
EXCAVATION METHODS TO BLAST OR NOT TO BLAST?
Use of mechanical or blasting methods depends on:• Volume of material• Hardness and structure• Schedule• Cost
?
GFR
11/16/2013
2
RISKS OF “NO BLASTING”
114 Mpa (16,500 psi)
RQD =96
RISK MANAGEMENT
SAFE & EFFICIENT
BLASTING
Ov
ers
igh
t1
RISK INCREASES WHEN ANY OF THESE SUPPORTING MEASURES AND CONTINUITY
OF PURPOSE ARE WEAK
3
4
2P
requ
alification
De
sig
n
Sp
ec
ifica
tion
s
BLASTING PROCESS
The Blasting Process
Rock Characteristics
INFLUENCINGFACTORS
Explosive Properties
Design Variables
Fragmentation
RESULTS
Broken Rock Profile
Damage
COMPLEXBLAST
PHYSICS
PHYSICAL PROPERTIES
Stress = F/A (MPa or psi)
D
Force (F) F
A
No Load
After LoadArea (A)
1/2 w
d
Direct Strain = d/D Tangential Strain = w/W Poisson's ratio = w/d
W
Young's Modulus = F/{d/D} (GPa or psi)
1/2 w
11/16/2013
3
ROCK PROPERTIES
Static Static Rock Density Young's Compressive Tensile Type (g/cm3) Modulus Strength
Strength(GPa) (MPa) (MPa)
Basalt 2.4-2.9 35-60 50-300 6-30 Sandstone 2.2-2.7 10-40 40-150 2-15 Siltstone 2.0-2.8 10-15 40-130 2-12 Coal 1.2-1.5 2-8 4-40
MODERN EXPLOSIVE TECHNOLOGY
1DANGER DETO NATEUR
DANGEROUS DE TONATOR
LP
Dang
er -
Exp
l osif
s
Te
nir e
loi g
Dan
ger -
Exp
l osi
fs
T
eni r
n
Exp
los i
ves
- Da n
gero
usl d
ren
Expl
osi v
e s -
Dan
ger
Modern explosives are much safer than the old "Dynamite and fuses" seen in Hollywood Movies
The effects of controlled construction blasts look nothing like the gasoline explosions used to create spectacular movie scenes
Commercial blasts are very controlled and carefully regulated
EXPLOSIVES
Molecular and Composites
EMULSIONS
Oxidizer Salts in Aqueous Phase,Oxidizer Salts in Aqueous Phase,Surrounded by Oil-Phase MatrixSurrounded by Oil-Phase Matrix
11/16/2013
4
SENSITIVITY
0
300
600
900
1200
1500
1800
2100
2400
2700
Bu
llet V
eloc
ity N
eede
d To
Initi
ate
(ft/s
ec)
PROJECTILE IMPACT TEST
DYNAMITE
H.E. Emulsion
ANFO
H.E.Watergel DYNAMITE VERSUS EMULSION EXPLOSIVE GAP SENSITIVITY
Dynamite Propagation Gap =18 to 24 inches
2 to 3 in.Open Gap
Detonator
RECEPTOR
DYNAMITE
EMULSION
DONOR
Emulsion Fails to detonate throughcardboard separation
Zero Gapwith Cardboard
DONOR
DONOR
RECEPTOR
RECEPTOR
EMULSION
EXPLOSIVES HANDLING AND SECURITYThe Canada Explosives Act (R.S.C., 1985, c. E-17)Canada Department of Natural Resources
Blasting Explosives and Initiation Systems -Storage, Possession, Transportation, Destruction and Sale Rules, March 2008Guidelines for Bulk Explosive Facilities –Minimum Requirements, July 2010
Transport Canada Transportation of Dangerous Goods Regulations and Transportation of Dangerous Goods Act.
BLAST EFFECTS
Shock Front
ReactionZone
UnreactedExplosive
Tensile StressCracks
Gas ExpansionHeaving &Displacement
Shock & Heave EnergyCracking and RuptureVibration and Overpressure
RADIAL CRACKING
RadialCompressive Stress
Limited Blasthole Crushing--in hard rock
TangentialTensile Stress
Stress/StrainWave Front
11/16/2013
5
ROCK STRUCTUREBedding PlanesPartings & JointsCaves and Mud SeamsFaults
JOINT EFFECTS
JOINTING EFFECTS ON CRACK PROPOGATION
Minor Joints or fissures
Open Joint
Radial CracksPass Through
Cemented Joints
Cemented Joint
CrackFronts areStopped byOpen Joints
ENERGY LOSS
Gas Venting Though Open Joints
B locky F ragm entationand poor breakage
Blast gases venting through open joints (Lost heave energy)
PLASTIC DEFORMATION
Deformation in Soft / Porous Material
Explosive energy is Lostto the Rock's Internal friction
LimitedRadialCracks
Hole Expands (Plastic Deformation)
-Argillite-Wollastonite-Marble-Conglomerate
11/16/2013
6
TUNNEL BLASTING
Drill Jumbo
LaserBeam
RockBolts
Face
DRILLING
Tunnel FaceInvert
Crown
LaserBeam
Shotcrete
RockBolts
LOADING2
1
Tunnel Face
BLAST AND VENTILATE
Tunnel Face
Tunnel Face
SUPPORTING TUNNEL
Load Haul DumpUnit
SCALE & MUCK
Tunnel Face
TEMPORARY GROUNDSUPPORT
5
Tunnel Face
6
Muck
Shotcrete
Air & Water
Material Hopper
Scaling
Shotcrete
Muck
Scaling
GROUND SUPPORT
FINAL SUPPORT7
8
Bolter
Tunnel Face
Shotcrete
Concrete Pump Surveyor
Tunnel Face
LaserSpot
Alignment Laser
11/16/2013
7
TUNNEL ROUND ELEMENTS
Spacing
Lifters
Buffer Holes
RibHoles
Burden
Smoothwall orBack Holes
Knee Holes
Cut
DRILLING GEOMETRY
CutHoles
Lifters
Buffer Holes
RibHoles
Smoothwall Arch Holes
KneeHoles
Perimeter HoleSpacing (S)
Burden (B)
SpringLine
GradeLine Loaded
Cut Holes
Burn Cut Detail
Void(unloaded)Cut Holes
TUNNEL BLASTING
Perimeter Hole Look-out Angle(Just enough for drill room)
Over drillthe burncut
ExpectedBreak
Round Advance
Cut holes
B u ffe r H o le
P e rim e te r (b ac k ) H o le
K ne e H o le
Lifter H ole
Designed overexcavation tocreate room for Drilling
MinimumTunnelDimensions
CUT METHODS
Fan Cut Round
1 2 3 4 5
1 2 3 4 5
6
6
7
7
11 11 1212
8 7 7 8
109910
Timing Sequence
Z1
2
3
4
5
56
6
3 " Reamed Hole
12"
14"
16"
18"
SHIELDED BLASTHOLE BURN CUTFOR 1 3/4 to 2 inch JUMBO ROUNDS
3'
6"
11/16/2013
8
EXAMPLE TUNNEL ROUNDS
SPRINGLINE
6 6 77
11
1720' 8"
10' 4"
SmoothwallHoles
Buffer Holes
Buffer Holes
z
z112 2
3
4
4
3
5
5
5
5
6 6
7
7
7
7
88
8
9
99
9
9
1010
1010
1111 11
11
11
11
10
10
10
12
1212
1212
13
13
13
13
13
13
13
13
13
1313
1314
1414141414
1414
14
8810 1011
15 15 1515 15 16 1717 16
68
7
SmoothwallHoles
2.5'
2.5'
2.5'
2.5'2.5'
CONTROLLING OVERBREAK
0.50
0.50
0.50
0.50
00.25
0.751.0
00.25
0.75
00.25
0.7500.25
0.75STRESSLEVEL
Effect of hole size and decoupling on rock stress -- after Hunter
6"
Fully Coupled
Distance to observation point
36"
Fully Coupled2"
Deoupled in air
Deoupled in water
BoreholeWall
SMOOTHWALL BLASTING
Desired Perimeter of Excavation
SMOOTHWALL MECHANICS
Detonating light charges along the perimeter of an excavation with minimum time separation creates tensile stress that cleaves rock at the desired limits of the excavation.
Some overbreak caused by joints and other structure in rock may occur
Minor radiial cracks
CompressionalStress
TensileStress
TYPICAL CHARGES
Buffer Load
Blasthole Load
Smoothwall Load
11/16/2013
9
DRILL LOOKOUT LIFTER CHARGES HEAVE ROCK
Lifter CollarPipe
L if te r H o leL if te r H o le
LiftersKnee Holes
OVERBREAK CAUSES CHARGE SEPARATION
Ground Shift Cut-off and Charge Separation in Jointed Rock MassCaused by:
OverloadingPoor Tamping or Plugging
11/16/2013
10
HIGH SHOCK EFFECTS
Shock Wave
Rock is DisplacedInto HoleHigh Pressure
Gas PenetratesInto Hole
PRE-COMPRESSION CAUSESIN DELAYED HOLES
COMPRESSIVE SHOCK WAVEHOLE TO HOLE
UndetonatedCharge
DetonatingCharge
Detonation Front
Plasma FrontOutruns Detonation
Plasma FrontCauses LateralPre-compression
Cross Section
Channel Effect
CONVENTIONAL VERSUS ELECTRONIC DETONATORS
SHIELDED BURN CUTS POWDER FACTOR Face area Powder Factor Range
(m2) (ft2) (Kg/m3) (lb/yd3)low high low high
3.7 40 3.3 7.0 5.5 11.74.6 50 2.9 6.3 4.9 10.55.6 60 2.7 5.7 4.5 9.66.5 70 2.4 5.2 4.1 8.77.4 80 2.0 4.4 3.4 7.48.4 90 1.8 3.8 3.0 6.59.3 100 1.5 3.1 2.5 5.3
18.6 200 1.2 2.6 2.0 4.427.9 300 1.0 2.1 1.6 3.537.2 400 0.8 1.8 1.4 3.046.4 500 0.8 1.6 1.3 2.7
25 50 75 100 125
1.0
2.0
3.0
kg/m3 lb/yd3
0.0
Face Area ( )m2
Face Area ( )ft 2
200
1.0
2.0
3.0
4.0
5.0
400 600 800 1000 1200
TUNNEL AND SHAFT ROUNDSSPECIFIC CHARGE (Powder Factor)Based on Area of Face
Adapted from Rock Blasting and Explosives Engineering, Persson et al. 1993
11/16/2013
11
CASE HISTORIES
CONNECTION TO EXISTING CONCRETE-LINED PENSTOCK
ResinDowels
11000
Existing Passage
Bulkhead
Wet Dry
2 0 0 0
Excavation Line
Elev. 558PlaftformBarrier
C o n c r e t eD e m o l i t i o n
I f D a m a g e d
ProbeHole
123457/8
9/10
10/11
11/12
6
12/13Existin gT u n n e lF a ce
>=1300
4400
5050
X
X XX
Buffer Holes
Trim Holes
Blastholes
Trim Holes
Buffer Holes
Trim Holes
For Two-StageRounds Blast the CenterFirst and then the Remaining PerimeterAdjust to size of Face
DRY LAKE TAP
3' Concrete--removedby mechanical methods
Shaft Liner
Last SlashBlast
12345678
general firingsequence
SLASH ROUND LOAD
NEVER TampPrimer Sticks
12 to 18 inch Collar
REGULAR BLASTHOLE LOAD
8-in.Collar
Collar Plug
Tamped1/2 stick(1 1/4 X 12)
Tamp only the last stick
(1 1/4 X 12)Emulsion or semigelatin dynamite
Trim Explosive1/2 Stick (Primer)
SMOOTHWALL PERIMETER
8-feet folded 200 Grain Detonating CordTaped to Primer Stick
(7/8 x 24)Trim Explosive@ > 0.33 lb/ft
TVA BLUE RIDGE DAM LOW LEVEL OUTLET
11/16/2013
12
CONDIT DAM LAKE TAP*Careful Probing*Redundancy
KOYNA WET LAKE TAPS
300
Pipe Spacers or wood blockingto align TemplateNormal to desireddrilling alignment(Do not cover holes)
Hoisting anchor boltwith attchment ringsecured with resincartridges
Hoist template intoposition with fourchain hoists
Hoisting Eye-Bolt
860 +/-
900 mm anchor boltssecured with resincartridges
INSTALLED TEMPLATE (Section A-A)
92mm Hole 2mm Pipe Wall +/-
636.4
800150
150
150
212.13 212.13
800
106.06
BOTTOM PLATE andLIFTING POINT Details
150
FOLSOM DAM TUNNEL
Roadway
Trunnion
RadialGate
Trunnion Anchor
6 x7'Air IntakeTunnel
32'
39'
89'
ConcreteMonolith
Potential Water Level
CAVATATION IN OUTLETS
11/16/2013
13
AERATION TUNNEL
Radial GatesRadial Gates
SprayWallSprayWallSprayWall
New 192.5-ft Tunnel
Down Stream Face SprayWall Portal
Existing 222.5-ft Tunnel
New 6 x 7 ' TunnelExisting 5-ft Round Tunnel
CONCRETE MONOLITH
Plan View Section
Down Stream View
Work PlatformWork Platform AccessAccessWalkwayWalkway
BLAST EFFECTS MEASUREMENTS
Criteria Definedby Scaled Tests
StrainStrainGaugeGauge
Strain vs Scaled Distance
10
100
1 000
10 000
1.0 1 0.0 10 0.0
Scaled Dis tance (ft/lb^0.5)
Mic
rost
rain
ininStrainPeak /900
FOLSOM DAM TUNNEL BLASTS
5 Sticks --(1 1/8 X 8) Non-NG Dynamite
BLASTHOLE LOAD
(7/8 x 24) NG-Trim Cartridge
SMOOTHWALL PERIMETER LOAD
Doubled 200 Grain Detonating Cord
Drill 4.5 feet.to break 4 feet
Stemming
Stemming
BLASTHOLE LOAD SmoothwallHoles
Open 3" Cut hole
6 ft
7 ft
LP Delay No.
1
2 1/2
5
2 1/24
6
10
1414
5
6
11
11
11
10
10
11
10
10
10
10
13
10
42 ms
42 ms Lead In
9
1/2
11 11
11
121213
11
3
1 1/2
4
9
3
8 8
7
22
1 1/2" Dia.holes
AERATION TUNNEL IN FOLSOM DAM
11/16/2013
14
FOLSOM DAM AERATION TUNNEL
Radial GatesRadial Gates
SprayWallSprayWallSprayWall
New 192.5-ft Tunnel
Do wn Stream Face SprayWal l Por ta l
Existing 222.5-ft Tunnel
N ew 6 x 7' Tun nelExisting 5-ft Round Tunnel
CONCR ET E M ONOLITH
Plan View Section
Down S tream View
Work PlatformWork Platform AccessAccessWalkwayWalkway
DETROIT SINKING CAISSONCaisson Toe
Pillars
R2
R3
R4
R1
RoomsP4
P1
P1
P2
P3
34'
Caisson
4.5 ft
3 ft
LoweredPosition
Line/Split Hole
5 ft
ROOM ROUND PILLAR ROUND
DECOUPLED CHARGES BLASTING PILLARS
11/16/2013
15
VIBRATION AND AIR-OVERPRESSUREPREDICTION AND
CONTROL
AIR-OVERPRESSURE LIMITS
USBM RECOMMENDATION from RI 84851
Lower Frequency Limit of Measuring System Maximum Level
0.1 Hertz high pass system Flat Response 134 Peak
2 Hertz high pass system Flat Response 133 Peak
5 or 6 Hertz high pass system Flat Response 129 Peak
C- weighted system for eventswith duration less than 2.0 sec.
Slow Response 105 Peak
LOGARITHMIC SCALE!
xpsiLogdBDecibels
109.220)( 910
dBxLogdBDecibels
thenpsipressureAbsoluteIf
151109.21.020)(
:,1.0
910
dBxLogdBDecibels
psipsipressureAbsoluteExample
130109.201.020)(
01.0)(:
910
pressurerealinincreasefoldatoequatesDecibelsinincreaseA 10%16
Noise Control
11/16/2013
16
AIR-OVERPRESSURE STEMMING AND DIRT & MAT COVER
NOISE MITIGATION EFFECT OF “CAP SCATTER”
Predominant frequenciesof motion > 40 Hz.
LP #8 (2,500 ms)
Detonator TimingError "Scatter"
NominalFiring Time(2,500 ms)
11/16/2013
17
ELASTIC STRAIN WAVES
DetonatingCharge or otherImpulsiveDisturbance
Wave extent
Abbreviations:SH = Shear wave, horizontalSV = Shear wave, verticalR = Rayleigh waveP = Compressional wave
R
SH
SV
P
ATTENUATION RATEEnergy is 25 timesEnergy is 25 timeslower in groundlower in ground1600 feet away1600 feet away
Distance 0 100 200 400 800 1600 (feet)
Energy 5.0 4.0 2.0 1.0 0.5 0.2 (ips)
Blast Charge Blast Charge Body WaveBody Wave
Surface WaveSurface Wave
VIBRATION AND AIR-OVERPRESSURE MONITORING
PLOTTING MOTION
1 2 3
TIME
AMPLITUDE
START
BASELINE
11/16/2013
18
Velocity of Particle Motion or Air Overpressure Plottedwith respect to time
Event Duration
BackgroundNoise
PeakAmplitudePP
V or
dB
L (p
si)
TIME
BaseLine
T1 CYCLE
IMPORTANCE OF FREQUENCY AND DURATION
15
10
5
-5
-10
-15
0
KHS45 - Feb 7LOMA PRIETA QUAKE - 1989
Duration = 36 SecondsMaximum PPV = 13.0 in/sFrequency = 0.8 HzDisplacement = 2.5 inches
0 10 20 30 40
Duration = 0.8 SecondsPPV = 3.2 in/sFrequency = 84 HzDisplacement = 0.006 inches
TIME (Seconds)15
10
5
-5
-10
-15
0
CONCRETE MOTION AT YUBA - NARROWS 2 PROJECT
Displacement and corresponding strain causedby Earthquake is 416 Times greater than that ofHigh-frequency Blast-Induced Motion
PPV(in/s)
PPV(in/s)
BLAST VIBRATION CRITERIA
1
FREQUENCY, Hz
PAR
TIC
LE V
ELO
CIT
Y, in
/s
0.1
0 .2
0.4
0.6
0.8
1
2
4
6
8
10
0.75 in/s
2.0 in/s
0.50 in/s
2 4 6 8 10 20 40 60 80 10030
40
10
USBM RI 8507 Safe PPV Curves - Dashed Lines
Plaster & LathDrywall
Constan
t 0.008 in
Displac
ement
Constan
t 0.03 in
Displac
ement
1) Intended for prevention of cosmetic damage in plaster-lath and gypsum drywall.
2) Too often misapplied to protect new or cured concrete structures.
3) These limits can make some work impossible or needlessly increase cost.
VIBRATION IMPACT TO ROCK
Reduction in Quality (%)
0
20
40
60
80
100
Peak Particle Velocity (mm/sec x 1000)
Peak Particle Velocity (in/sec)
0 1 2 3 4
Approximate adjustment of rock mass quality after vibration. After Page 1987
0 40 79 118 157
"weak" rockQ<4
MRMR<20
"fair" rockQ-4
MRMR - 56
"good" rockQ>50
MRMR > 80
Effect(in/s) (mm/s)
10 254 No fracturing of intact rock10 to 25 254 to 635 Minor tensile slabbing will occur25 to 100 635 to 2540 Strong tensile and some radial cracking
> 100 >2540 Complete breakup of the rock massAfter Bauer and Calder (1971)
Peak Particle Velocity
11/16/2013
19
ORIARD Mass Concrete PPV LimitsConcrete Age Allowable
From Batching PPV - mm/s (in/s)
0 to 4 hours 102 (4) x DF4 hours to 1 day 152 (6) x DF1 to 3 days 229 (9) x DF3 to 7 days 305 (12) x DF7 to 10 days 375 (15) x DF10 days or more 508 (20) x DF
Distance Factors (DF):
Distance = 0 – 15 m (0 – 50 ft) DF = 1.0Distance = 15 – 46 m (50 – 150 ft) DF = 0.8Distance = 46 – 76 m (150 – 250 ft) DF = 0.7Distance > 76 m (250 ft) DF = 0.6
Oriard and Coulson – 1980
Distance Factors are intended to reduce PPV levels at greater distances to account for higher displacements caused by lower frequencies.
Must also consider:
2) Block motion and ground rupturing potential.
1) Structure height and confinement
2) Condition or structure and reinforcement.
DISPLACEMENT AND STRAIN
0.7 in/s@ 57 Hz
0.15 in/s@ 10 Hz
1) Displacement at low frequency motion greater than at peak!
2) Time history reveals more than summary of motion at PPV
Displacement = PPV / (2 pi f )
RELATIVE EFFECTS
15-lbSledge
Hammer
18-WheelTruck Jump 20-mph
Wind 10 deg.Temp Chg. 50-mph
Wind 7-dayWeather
Chg.
Safe Limitfor Drywall Safe Limit
forConcrete
AspectSeismic
PPV
0
2
4
6
8
10
12
14
16
18
20
PPV
2.02.02.0
20.0 ips20.0 ips20.0 ips
5.125.125.12
0.550.550.55 0.50.50.52.62.62.6 3.23.23.2
6.76.76.75.05.05.0
RELATIVE VIBRATION IMPACTS
More than 20 timeshigher than motionpredicted at Propertiesclosest to CSO Blasts
Buried Raw Eggs and LightbulbsBuried Raw Eggs and LightbulbsSurvive 5.0 in/s PPVSurvive 5.0 in/s PPV
11/16/2013
20
VIBRATION AND NOISE CONTROL* Structural and Cosmetic Damage* Human Response* Animal Response
ACME
GFR
HUMAN RESPONSE
0.1 1 10 100 1000
Parti
cle
velo
city
(in/
sec)
(mm
/sec
)
Stronglyperceptible
ISO reduced comfort
Severe
Distinctlyperceptible
Barelyperceptible
0.01
0.1
1
10
1
10
100
Exposure time (s)
After Wiss and Parmalee (1974)
ANIMAL RESPONSE
"Pete" the Black Rhino"Pete" the Black RhinoElephantsElephantsRed PandasRed PandasNaked Mole RatsNaked Mole Rats
DRILLING SMALL HOLES FOR SHAFT BLAST
11/16/2013
21
REDUCING CHARGE PER DELAY
SeparateTrunklinefor eachquadrant
+0
+42+84
+126
PREDICTING PPVm
WDKPPV
Where:
K and m are constants defining initial vibration and rate of attenuation
D = Distance between blast and prediction location (m or ft)
W = Maximum charge weight per 8-millisecond delay (kg or lb)
DIMENSIONAL SIMILITUDE
W 1 = 100 kg
Point of PPV Measurement
W 2 = 1 kg
D = 100 m
D = 10 m
Point 2 Point 1
so PPV 1 PPV 2
PPV = K (Ds)m
101
10 Ds 210100
100 Ds 1
Ds 1 = Ds 2
LINEAR IN LOG-LOG SCALE
m
WDKPPV
WDDs
KLogDsLogmPPVLog
bxay Log Ds
Log ppv
Slope = mLog K
11/16/2013
22
ORIARD PPV RANGE 6.1 sDKPPV
6.1 sDKPPV
6.1
160
WDPPV
Where: D = Distance (ft)W = Charge‐per‐Delay (lb)
6.1
1141
WDPPV
Where:D = Distance (m)W = Charge‐per‐Delay (kg)
CASE STUDYLEGEND
- Plaintiff's Home
- Monitoring Location
2510'
1565'
Location ofMiningBoundry(April 2002)
SCALE
0 500' 1000'
N1
2
3
5
6
4
- Monitoring Location No.1
CURVE SLOPE
Harrod PPV Curve
0.010
0.100
1.000
10.000
100.000
1000.000
1.0 10.0 100.0 1000.0 10000.0
Ds
PPV PreSeisTek
Blastech
86.0
7.10
sDPPVFitBest
Based on 329 Data Points. Correlation coefficient = 0.782
86.03.22%95 sDPPVUpper
CRACK DILATION
11/16/2013
23
COMPARABLE EFFECTS
Comparative Changes in Crack Widthmicro inches
Crack Location Outside Inside Basement Inside Bedroom notes(Wall Material) (Brick wall) (Concrete Block) (Dry Wall )
Effect
lightOccupant 400 250 200 adjacentActivity pounding
Wind??? 50
Weather/ (10,000) 6000 (750) (daily)Environmental (750)
Blasting 200 200 50 0.14 ipsmaximum
Wind
* Environmental effects on existing cracks in structures were 50 times greater than those caused by blasting
DAMAGE CAUSES
Temperature ChangesHumidity DifferencesSoil Expansion or Collapse Water DamageWind and Weather Aging ProcessesWear and Tear
CADOMIN ALBERTA BLASTING NEAR NEW CONCRETE
11/16/2013
24
CHARACTER OF MOTION
8 ft
Blast-ProofForm and NewConcrete
Shot rock left against toe of face to suppress flyrockand air-overpressure
SUMP AREA
PPV > 30 in/sFrequency: >1,000 HzDisplacement: 0.0048 in(Hair thickness: 0.008 in)
BLASTING NEAR SOLDIER PILES
Direct rupturing causes damage.High PPV at high frequency motion with light decoupled charges does not!
BLASTING NEAR FREEZE PIPES BLASTING NEAR FREEZE PIPES
11/16/2013
25
STRAIN CALCULATIONS CHARGE RELIEF AND SWELL* Free Face* Orientation* Timing
VbVs = 1.3 Vb
Swell factor Principle
If swell factor (SF) = 1.3Swelled Volume (Vs) = Vb x SF
Swelled volume (Vs) Bench volume (Vb) 1 .2 m (4 ft)
RISK MANAGEMENT
SAFE & EFFICIENT
BLASTING
Ov
ers
igh
t
1
RISK INCREASES WHEN ANY OF THESE SUPPORTING MEASURES AND CONTINUITY
OF PURPOSE ARE WEAK
3
4
2
Preq
ualificatio
n
De
sig
n
Sp
ec
ifica
tion
s
BEST MANAGEMENT PRACTICES
• Evaluate Area Property- Pre-construction Inspections
• Apply Blasting Controls- Charge Weight Limits- Noise Control Measures
• Public Communication- Project Hotline- Open Meetings
• Government Approvals• Perform Work Safely• Continuous Blast Effects Monitoring
11/16/2013
26
SUCCESSFULLY MANAGING HIGH-RISK BLASTING WORK
There are four layers of expertise:
The first layer starts with designers who develop specifications, geotechnical reports, and other documents that:
1) define challenges of the work; 2) limit allowable methods; 3) specify performance requirements and;4) establish experience requirements for key
participants
SUCCESSFULLY MANAGING HIGH-RISK BLASTING WORK
The third layer of risk management is expected from third-party blasting / vibration consultants representing the contractor.
SUCCESSFULLY MANAGING HIGH-RISK BLASTING WORK
The last layer of risk management is delivered by a third-party construction manager, supported by inspectors, project designers, and additional specialists as needed.
QUESTIONS?