Alex Vyazmensky Ph.D.
https://sites.google.com/site/alexvyazmensky/http://kz.linkedin.com/in/vyazmensky
Numerical Modelling of Surface Subsidence Associated with Block Cave Mining Using a FEM/DEM Approach
1
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Presentation Outline
• Problem Statement: Block Caving Mining and Associated
Surface Subsidence
• Research Objectives
• Modelling Methodology
• Conceptual Study of Factors Controlling Surface Subsidence
Development
• Caving Induced Instability in Natural and Man-made Slopes
3
Problem Statement
Block Caving and Associated Subsidence
(modified after Sandvik Tamrock block caving animation)
Block cave mining is characterized by caving andextraction of a massive volume of ore whichtranslates into a formation of major surfacedepression or subsidence zone directly aboveand in the vicinity of the mining operations.
The ability to predict surface subsidenceassociated with block caving mining isimportant for mine planning, operational hazardassessment and evaluation of environmentaland socio-economic impacts.
Owing to problems of scale and lack of access, the fundamental understanding of the complex rock mass response leading to subsidence development is limited as are current subsidence prediction capabilities.
Current knowledge of subsidence phenomena can be improved by employing numerical modellingtechniques in order to enhance our understanding of the basic factors governing subsidence development; essential if the required advances in subsidence prediction capability are to be achieved.
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Northparkes mine, Australia
Subsidence Examples
San-Salvador mine, Chile
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6
Research Strategy
Research Objectives and Strategy
RESEARCH OBJECTIVES NUMERICAL
ANALYSISRESEARCH OUTCOME
conceptual study of
factors controlling
surface subsidence
development
conceptual study of
caving induced
instability in natural
slopes
case study of partial
failure of northern pit
wall at Palabora mine
identification of
characteristic
subsidence
development
mechanisms,
comparative analysis
and ranking of factors
controlling surface
subsidence
development
assessment of critical
deformation thresholds
leading to slope
instability
new FEM/DEM-DFN
methodology for
numerical analysis of
surface subsidence
associated with block
cave mining
investigate block caving
induced failure
mechanisms leading to
slope instability in large
engineered slopes
introduce new
methodology for numerical
analysis of surface
subsidence associated
with block cave mining
improve understanding of
block caving subsidence
phenomenon
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Modelling Methodology
Toolbox for Subsidence Analysis
Current approaches to assessing surface subsidence associated with block cavingmining includes empirical, analytical and numerical methods:
• Empirically based block caving subsidence estimates include “rules of thumb”and experience based design charts linking angle of brake, rock mass ratingand other parameters.
• Analytical methods include limit equilibrium solutions for specific failuremechanisms (e.g. progressive sub-level caving of an inclined orebody).
• Different modelling approaches exist, based on the concept that thedeformation of a rock mass subjected to applied external loads can beconsidered as being either continuous or discontinuous. The main differencesbetween the various analysis techniques lie in the modelling of the fracturedrock mass and its subsequent deformation.
Numerical techniques being inherently more flexible and sophisticated providean opportunity to improve understanding of subsidence phenomena andincrease accuracy in subsidence predictions.
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ABAQUS
Beck, 2007
Continuum Modelling
FLAC3D
Connors, 2006
Modelling Approach
Numerical Method
Rock Mass Representation Rock Mass Failure Realization
Continuum FDM, FEM continuous medium flexural deformations, plastic yield
11
Discontinuum Modelling
PFC 3D 3DEC
Modelling Approach
Numerical Method
Rock Mass Representation Rock Mass Failure Realization
Discontinuum DEM assembly of deformable or rigid blocks
blocks movements and/or blocks deformations
assembly of rigid bonded particles
bond breakage, particle movements
Gilbride et al, 2005 Brummer et al, 2005
New Numerical Modelling Approach
A state-of-the-art combined continuum-discrete element code ELFEN is employed asthe principal modeling tool. The code allows the caving process to be simulated as abrittle fracture driven continuum-discontinuum transition with thedevelopment of new fractures and discrete blocks.
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Most natural rocks subjected to engineering analysis are brittle; failure in such rocksis a result of brittle fracture initiation and propagation.
Continuum and discontinuum modelling approaches provide approximations ofbrittle fracturing to some degree, none of them however offer realistic representationof the actual brittle fracturing phenomena which involves fracture growth,propagation and material fragmentation.
Examples: caving initiation topplingblasting
Modelling Approach
Numerical Method
Rock Mass Representation
Rock Mass Failure Realization
Hybrid Continuum-Discontinuum
FEM/DEM continuous medium
degradation of continuum into discrete deformable blocks through fracturing and fragmentation
FEM/DEM Modelling Examples
Rock bridge failure Step-path drive open pit wall failure
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Link to animation
Link to animation
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Given the complexity of modeling mine scale problems and generallyvariable quality of geological/geotechnical data available - a number ofsimplifications and assumptions will be necessary. There is a risk of“oversimplifying” the problem.
Aiming to develop fundamental understanding of mechanismscontrolling subsidence development on smaller scale conceptual models.Apply new knowledge to the analysis of a case study.
CURRENT RESEARCH FOCUSED ON CONCEPTUAL ANALYSIS
• Back analysis of selected case studies.
Modelling Options:
• Conceptual analysis.
Modelling Strategy for Subsidence Analysis
modelling studies done to date were largely oriented towards providing site specific subsidence predictions.
Rock Mass Representation in FEM/DEM 15
Equivalent Continuum
Mixed Approach
Discrete Network
• jointed intact rock mass system is represented as a continuum with reduced intact rock properties to account for presence of discontinuities;
• rock mass properties can be deduced from one of the rock mass classification systems such as RMR, Q or GSI;
• this approach does not consider kinematic controls of the failure.
• rock mass is represented as an assembly of discontinuities and intact rock regions;
• intact rock properties can be established based on laboratory tests and the pattern of discontinuities can be determined from field mapping/borehole logging data or stochastic modeling;
• not feasible to consider high density of fractures for models larger than pillar/bench scale
• necessary simplification for analysis of large scale problems;• resolution of fractures should be sufficient to capture failure kinematics;• rock mass properties can be deduced from one of the rock mass classification
systems and then calibrated against known response.
Possible Approaches to Rock Mass Representation in FEM/DEM Modeling Context:
selected for current analysis
16
ore
block
FracMan DFN model
3D model 2D trace plane
2D ELFEN model
Properties calibration criteria:
Constrain:
Caveability Laubscher’s caveability chart
Cave development progression
Conceptual model of caving by Duplancic & Brady (1999)
Subsidence limits
Mining experience
Constraint
fractures
exported
into
ELFEN
model response evaluation
Modelling Methodology - Typical Model Setup
ore block is undercut and fully extracted
RMC Based Equivalent Continuum Properties
RMC System
Estimates of Rock Mass Strength and Deformability Characteristics
Reference
RMR
40/)10(10 RMRmE (GPa)
2/5 RMR
RMRc 5 (kPa)
Serafim & Pereira (1983)
Bieniawski (1989)
Q
31
10 cm QE (GPa)
1tan"" 1 w
a
r J
J
J
100
1"" c
n SRFJ
RQDc
(MPa)
where:
)100/( cc QQ - normalized Q;
c – uniaxial compressive strength (MPa)
Barton (2002)
GSI
)11/)1560((1
2/102.0
GSIDime
DEE (MPa)
1'3
1'3'
6212
6sin
a
nbb
a
nbb
msamaa
msama
aamsamaa
msmasac
a
nbb
a
nbnbci
216121
121
1'3
1'3
'3'
(MPa)
where:
Ei – intact rock Young’s modulus;
D - disturbance factor;
a, s, mb – material constant;
cn /'max33 , '
max3 - upper limit of confining stress
Hoek et al. (2002)
Hoek & Diederichs
(2006)
17
18
(a) Deformability modulus
10.0
17.8
31.6
56.2
18.4
31.2
43.9
52.8
11.17 17.7
26 37.4
0
10
20
30
40
50
60
50 60 70 80
Defo
rmab
ilit
y m
od
ulu
s, G
Pa
RMR
RMR
GSI - tunnel (-200m)
Q
(b) Friction angle
30
35
40
45
52.755 56.6
57
4545 45
45
0
10
20
30
40
50
60
50 60 70 80
Fri
cti
on
an
gle
, d
eg
rees
RMR
RMR
GSI - tunnel (-200m)
Q
(c) Cohesion
0.25
0.3 0.35 0.41.4
22.9
4.9
1.6
4.7
15.1
0
2
4
6
8
10
12
14
16
18
20
50 60 70 80
Co
hesio
n, M
Pa
RMR
RMR
GSI - tunnel (-200m)
Q
52 / 80
(d) Tensile Strength
0.31 0.330.330.17
0.8 1.61.3
3.9
12.5
0.65
1.8
6.3
0.13
0.391.25
4.3
0
5
10
15
50 60 70 80
Ten
sile s
tren
gth
, MP
a
RMR
RMR
GSI - tunnel (-200m)
Q
Q - 50% cut-of f
Q - 90% cut-of f
43.4 / 80 21.7 / 80
RMC Based Equivalent Continuum Properties
Q 6
.2 (
70%
c.o
.)
RM
R 7
0
Rati
ng
Rock Mass Properties
Defo
rma
bilit
y m
od
ulu
s,
E,G
Pa
Co
he
sio
n,
ci,
MP
a
Fri
cti
on
,
I
deg
ree
s
Te
nsil
e
str
en
gth
,
t,
MP
A
RMR70 31.6 0.35 40 0.33
Q 6.2 17.7 4.7 451.18
(70% c.o.)
RMC Based Equivalent Continuum Properties 19
block undercutting
HR=20
HR=10
HR=30
HR=40 HR=50
Subsidence Simulation Example - Caving Initiation 20
21
surface
subsidence,
m
50m
70°
20°
Subsidence Simulation Example - Crater Formation
Evolution of vertical displacements (0.1 – 1m)
Link to animation
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Conceptual Study of Factors Governing Subsidence Development
Conceptual Study Strategy
Factors affecting surface subsidence development
Joint Orientation & Persistence
Faults Rock Mass
Strength
Stress Ratio, K
Block Depth
Geological Domains
Extraction volume
Series of conceptual numerical experiments investigating relative significance of the above factors
Ranking factors in terms of their influence on subsidence footprint
Worst case scenarios
Influence Matrix
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Identification of characteristic subsidence mechanisms
24Conceptual Study Example: Effect of Joint Orientation
Vyazmensky et al, MassMin2008
90°
0°
10°
80°
20°
70°
Direction of cave propagation towards the surface, location of the cave breakthrough and the mechanisms of near surface rock mass failure are strongly controlled by the joint orientation
10%
25
20%
26
30%
27
40%
28
50%
29
60%
30
70%
31
80%
32
90%
33
34Conceptual Study Example: Effect of Joint Orientation
Legend:
rotational failure;
translational failure
active rock mass
movement
developing rock
mass failure
35% ore extraction 50% ore extraction 60% ore extraction
0°
50m
90°
0°
5°
80°
10°
70°
20°
4°
9°
90°
0°
10°
80°
20°70°
ore extraction
Joint orientation controls not only the cave propagation direction but also playsa significant role in a manner the rock mass is mobilized by the caving
35Conceptual Study Example: Effect of Joint Orientation
• Combination ofvertical and horizontal
sets results in nearlysymmetrical subsidenceprofile
• Subsidence asymmetryis strongly controlled bythe inclination ofsub-vertical andsub-horizontal sets.
• Major subsidence asymmetry is observed in the dip direction of the sub-vertical set, in this area rock mass fails through flexural and block toppling and detachment and sliding of major rock segments
• In order to quantify the extent of major surface subsidence deformations 10cm displacement threshold is adopted. It is assumed that this threshold limits the zone of major surface disturbances
angle delineating major (≥10cm) surface displacements
AV © 2008
36
0
10
20
30
40
50
60
70
80
90
100
-250 -200 -150 -100 -50 0 50 100 150 200 250
Ore
extr
acti
on
, %
Extent of 10cm surface deformations, m
BC -YYBC -XX
0
10
20
30
40
50
60
70
80
90
100
-250 -200 -150 -100 -50 0 50 100 150 200 250
Ore
extr
acti
on
, %
Extent of 10cm surface deformations, m
J1 - YY
J1 - XX
90°
0°
0
10
20
30
40
50
60
70
80
90
100
-250 -200 -150 -100 -50 0 50 100 150 200 250
Ore
extr
acti
on
, %
Extent of 10cm surface deformations, m
J2 - YY
J2 - XX
10°
80°
20°70°
Evolution of zone of major (≥10cm) vertical (YY) and horizontal (XX) surface deformations with continuous ore extraction
Conceptual Study Example: Effect of Joint Orientation
• Major subsidence deformations develop in a relatively rapid manner related to a quick mobilization of massive rock mass segments
• About 90% of maximum surface displacements are achieved by 50% ore extraction
Extent of of major vertical (≥10 cm) surface displacements
Conceptual Study Example: Effect of Joint Orientation
Change in joint orientation causes an increase in the total major surface deformations extent of up to 30%
207234
268
100%
113%
129%
0
50
100
150
200
250
300
350
0
50
100
150
200
250
300
350
To
tal exte
nt o
f 10cm
vert
ical
su
rface d
isp
lacem
en
ts
no
rmalized
b
y B
ase C
ase, %
To
tal exte
nt o
f 10cm
vert
ical
su
rface d
isp
lacem
en
ts,
m
BC J1 J2
218235
308
100%
108% 141%
0
50
100
150
200
250
300
350
0
50
100
150
200
250
300
350
To
tal exte
nt o
f 10cm
ho
riz.
su
rface d
isp
lacem
en
ts
no
rmalized
b
y B
ase C
ase, %
To
tal exte
nt o
f 10cm
ho
riz.
su
rface d
isp
lacem
en
ts,
m
BC J1 J2
-112
95
-123
111
-161
107113%
144%
117%
110%
100%
100%
-300 -200 -100 0 100 200 300
-250 -200 -150 -100 -50 0 50 100 150 200 250
Extent of 10cm surface vertical displacements in relation to block centre, normalized by Base Case, %
Extent of 10cm surface vertical dispacements in relation to block centre, m
BC
J1
J2
BC
J1
J2
-118
100
-123
112
-201
107107%
170%
116%
104%
100%
100%
-300 -200 -100 0 100 200 300
-250 -200 -150 -100 -50 0 50 100 150 200 250
Extent of 10cm surface horizontal displacements in relation to block centre, normalized by Base Case, %
Extent of 10cm surface horizontal displacements in relation to block centre, m
BC
J1
J2
BC
J1
J2
207234
268
100%
113%
129%
0
50
100
150
200
250
300
350
0
50
100
150
200
250
300
350
To
tal exte
nt o
f 10cm
vert
ical
su
rface d
isp
lacem
en
ts
no
rmalized
b
y B
ase C
ase, %
To
tal exte
nt o
f 10cm
vert
ical
su
rface d
isp
lacem
en
ts,
m
BC J1 J2
218235
308
100%
108% 141%
0
50
100
150
200
250
300
350
0
50
100
150
200
250
300
350
To
tal exte
nt o
f 10cm
ho
riz.
su
rface d
isp
lacem
en
ts
no
rmalized
b
y B
ase C
ase, %
To
tal exte
nt o
f 10cm
ho
riz.
su
rface d
isp
lacem
en
ts,
m
BC J1 J2
-112
95
-123
111
-161
107113%
144%
117%
110%
100%
100%
-300 -200 -100 0 100 200 300
-250 -200 -150 -100 -50 0 50 100 150 200 250
Extent of 10cm surface vertical displacements in relation to block centre, normalized by Base Case, %
Extent of 10cm surface vertical dispacements in relation to block centre, m
BC
J1
J2
BC
J1
J2
-118
100
-123
112
-201
107107%
170%
116%
104%
100%
100%
-300 -200 -100 0 100 200 300
-250 -200 -150 -100 -50 0 50 100 150 200 250
Extent of 10cm surface horizontal displacements in relation to block centre, normalized by Base Case, %
Extent of 10cm surface horizontal displacements in relation to block centre, m
BC
J1
J2
BC
J1
J2
207234
268
100%
113%
129%
0
50
100
150
200
250
300
350
0
50
100
150
200
250
300
350
To
tal exte
nt o
f 10cm
vert
ical
su
rface d
isp
lacem
en
ts
no
rmalized
b
y B
ase C
ase, %
To
tal exte
nt o
f 10cm
vert
ical
su
rface d
isp
lacem
en
ts,
mBC J1 J2
218235
308
100%
108% 141%
0
50
100
150
200
250
300
350
0
50
100
150
200
250
300
350
To
tal exte
nt o
f 10cm
ho
riz.
su
rface d
isp
lacem
en
ts
no
rmalized
b
y B
ase C
ase, %
To
tal exte
nt o
f 10cm
ho
riz.
su
rface d
isp
lacem
en
ts,
m
BC J1 J2
-112
95
-123
111
-161
107113%
144%
117%
110%
100%
100%
-300 -200 -100 0 100 200 300
-250 -200 -150 -100 -50 0 50 100 150 200 250
Extent of 10cm surface vertical displacements in relation to block centre, normalized by Base Case, %
Extent of 10cm surface vertical dispacements in relation to block centre, m
BC
J1
J2
BC
J1
J2
-118
100
-123
112
-201
107107%
170%
116%
104%
100%
100%
-300 -200 -100 0 100 200 300
-250 -200 -150 -100 -50 0 50 100 150 200 250
Extent of 10cm surface horizontal displacements in relation to block centre, normalized by Base Case, %
Extent of 10cm surface horizontal displacements in relation to block centre, m
BC
J1
J2
BC
J1
J2
37
Resultant surface profiles
• Rotation of the jointpattern shifts centre ofsurface depression;
• Depth of the subsidencecrater is related to theextent of the rock massmobilized by the failure,- larger extent ofrock mass mobilizationresults in shallower
crater
Conceptual Study Example: Effect of Joint Orientation
90°
0° 10°
80°20°
70°
-80
-70
-60
-50
-40
-30
-20
-10
0
-350 -250 -150 -50 50 150 250 350
Vert
ical d
isp
lacem
en
ts,
m
Distance from block centre, m
Base case
J1
J2
0, -55
9.4, -44.5
10, -50
Lowest point coordinates
38
39
J2
-0.3
-0.25
-0.2
-0.15
-0.1
-0.05
0
-300 -250 -200 -150 150 200 250 300
Vert
ical d
isp
lacem
en
ts,
m
Distance from block centre, m
-0.38
J2
BC
BC BC
J1
J1
J1J2
J2
J2
J2
0
0.05
0.1
0.15
0.2
0.25
0.3
-300 -250 -200 -150 150 200 250 300
Ho
rizo
nta
l d
isp
lacem
en
ts, m
Distance from block centre, m
0.9
far-field displacements
Conceptual Study Example: Effect of Joint Orientation
The least amount of surface displacements is exhibited by the Base Case model (90°/0°), so that only minor horizontal displacements of about 1cm are observed 100m from the caving boundaries (150m from block centre).
The largest amount of displacements are observed for J2 (70°/20°) model, where 1cm horizontal displacements are noted as far as 200m westwards from the caving boundaries. Surface displacements in the far-field are generally mirror the trends observed for major surface deformations, showing strong asymmetry in the dip direction of the sub-vertical/gently dipping set.
From the point of view mine infrastructure placement it is important to appreciate the amount of surface displacements at some distances from the area of the imminent failure (caving boundary and immediate vicinity).
Conceptual Study Example: Effect of Joint Orientation - Conclusions
• Well defined, persistent, vertical to steeply dipping joints govern the direction ofcave propagation and the mechanism of near surface rock mass mobilization.
• The shallower the dip of these joints the more inclined from vertical is the cavepropagation direction and the more asymmetrical are the surface deformations.
• In cases where multiple well defined and persistent steeply dipping sets arepresent the steepest set will generally have the predominant influence.
• Major subsidence asymmetryis observed in the dip directionof the sub-vertical/steeply dipping set,where joints are inclined towardsthe cave, the rock mass failsthrough block-flexural andblock toppling and detachment and sliding of major rock segments.
• Depending on joint inclination the joint persistence may have a very significanteffect on surface subsidence induced by block caving.
53° 74°
40
41Subsidence Simulation Example - Influence of fault
Geometry Evolution of vertical displacements (0.1 – 1m)
AV © 2008
50m
100m
60°
Subsidence crater developmentLink to animation
50m
100m
60°
60°
60°
150m
90°
0°
90°
0°
90°
0°
0-100 -50-150-200-250 10050 150 200 250 300-300
fault location prior to caving
73°
10cm displ. contours vertical
horizontal
Legend:
angle of fracture initiation
73°
73°
61° 76°
73° 74°
former fault position
Effect of Fault Location 42
Conceptual Study Example: Effect of Fault Location and Inclination
• Steeply dipping faults, daylighting into the cave and located within an area of imminent caving are likely to be caved and are unlikely to play any major role in the resultant subsidence.
• Faults partially intersecting the caving area may create favourable conditions for failure of the entire hanging wall.
• Depending on rock mass fabric faults located in the vicinity of the caving zone may have minimal influence or decrease the extent of the area of subsidence deformations.
• A topographical step in the surface profile is formed where the fault daylights at the surface.
• Inclination of the fault partially intersecting the caving area controls the extent of surface subsidence deformations. Low dipping faults will extend and steeply dipping fault will decrease the area of surface subsidence.
43
44Example of Surface Subsidence Simulation
CAVE ARREST, CROWN PILLAR FAILURE and RESULTANT SUBSIDENCE
50m
Link to animation
45Conceptual Study Results Synthesis
46Conceptual Study Results Synthesis
47Conceptual Study Results Synthesis
48Conceptual Study Results Synthesis
49
Conceptual Study of Factors Governing Subsidence Development
cave propagation
induced displacements field
potential slope instability
AV © 2007
AV © 2007
AV © 2007
200m
200m
200m
200m
Simplified applied displacements modeling approachblock caving inducedslope failure
50Block Caving and Natural Slopes: caving close to slope toe
AV © 2007
AV © 2007
surface inclination 15 degrees
Questa mine
simulated failure pattern resembles the deformations observed in similar settings at Questa mine
51
CONCEPTUAL MODEL
Block Caving and Natural Slopes: caving within slope
Animation
52
750m
400m
persistent jointsdaylighting into the cave
rock bridges
block cave
CONCEPTUAL MODELembedded animation
SLOPE IS STABLE WITHOUT CAVING
Conceptual Study of Block Caving Induced Step-path Driven Failure in Large Open Pit Slope
Numerical Analysis of Block Caving Induced Instability in Large Open Pit Slopes: A Finite Element / Discrete Element Approach
Fracturing
regions
50o
300m 300m
400m
750m
75m
RB600
RB300
10 excavation stages
60o
history point
History point
53Conceptual Study of Block Caving Induced Step-path Driven Failure in Large Open Pit Slope
-0.2
-0.15
-0.1
-0.05
0
-5
0
5
10
15
20 22 24 26 28 30 32 34 36
RB600
RB300
differential XY displ. at
surface outcrop
0
50
100
150
200
250
300
350
400-15
-10
-5
0
σyy (50m below pit bottom)
crown pillar thickness, m
No
rm. sh
ea
r str
ess X
Y, M
Pa
Ve
rtic
al s
tre
ss Y
Y, M
Pa
ΔX
Y d
isp
l. a
t su
rfa
ce
ou
tcro
p, m
Cro
wn
pill
ar th
ickn
ess, m
simulation time, num.sec
RB600 failure RB300 failure
end o
f pit e
xcavation
54Conceptual Study of Block Caving Induced Step-path Driven Failure in Large Open Pit Slope
-100
-80
-60
-40
-20
0
0
20
40
60
80
100
2 4 6 8 10
Cro
wn
pill
ar d
estr
essin
g, %
Rem
ain
ing
cro
wn p
illar
thic
kn
ess , %
% rock bridges
first rock bridge failure
last rock bridge failure
destressing, %
thickness, %
crown pillar:
55
-15
-10
-5
0
20 22 24 26 28 30 32 34 36
M1 M2 M3
M4 M5
Simulation time, num.sec
Vert
ical s
tress Y
Y, M
Pa
Fig. Error! No text of specified style in document..1 Variation of vertical stress in the crown pillar (50m below pit bottom) for models M1-M5
two rock bridges three rock bridges
four rock bridges
56
57
Min
e
infr
as
tru
ctu
re
Surface subsidence
Case Study - Palabora mine
~160°
A
A
Note limited extend of the failure
beyond pit rim
Lateral release
DFN based analysis (section A-A)
Case Study - Palabora mine 58
approximate failure
crest location
98 m
approximate failure
crest location
Case Study - Palabora mine 59
Key contributions
• A new FEM/DEM-DFN modelling approach was developed and successfully applied to block caving subsidence and caving - large open pit interaction analysis. This methodology allows physically realistic simulation of the entire caving process from caving initiation to final subsidence deformations.
• Limitations of the rock mass classifications properties output were highlighted and a procedure for calibration of rock mass classifications based properties for FEM/DEM-DFN subsidence analysis was devised.
• Through a comprehensive conceptual numerical modelling analysis majoradvances were gained in our understanding of the general principles of blockcaving induced subsidence development and the role of major contributingfactors.
• The principles of step-path failure development in large open-pit - cavingmining environment were investigated using a proposed “total interaction”approach to modelling data interpretation.
• Applicability of the FEM/DEM-DFN modelling for practical engineeringanalysis was demonstrated in the preliminary simulation of the Palabora minefailure.
60
“Role of Rock Mass Fabric and Faulting in the Development of Block Caving Induced Surface Subsidence” Vyazmensky A., Elmo D., Stead D. Rock Mechanics and Rock Engineering Journal. Volume 43, Issue 5 (2010), 533 - 556.
“Numerical Analysis of Block Caving Induced Instability in Large Open Pit Slopes: A Finite Element / Discrete Element Approach” Vyazmensky A., Stead D., Elmo D., Moss, A. Rock Mechanics and Rock Engineering Journal. Volume 43, Number 1 / February (2010), 21 - 39.
“Numerical analysis of the influence of geological structures on the development of surface subsidence associated with block caving mining” A. Vyazmensky, D. Elmo, D. Stead & J. Rance. MassMin 2008. Lulea, Sweden. 857-866. (2008).
“Combined finite-discrete element modelling of surface subsidence associated with block caving mining” Vyazmensky A., Elmo D., Stead D. & Rance J. Proceedings of 1st Canada-U.S. Rock Mechanics Symposium. Vancouver, Canada. 467-475. (2007).
"Numerical modeling of surface subsidence associated with block cave mining using a FEM/DEM approach" PhD thesis SFU'08 PDF
61Publications
SFU Resource Geotechnics Research GroupRio TintoRockfield Technology Ltd.Golder Associates Ltd.
62Acknowledgements
