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EMPIRICAL DESIGN METHODS – UBC GEOMECHANICS RESEARCH –CERM3 WORKSHOP
R. PAKALNIS - UBC
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RELATE TO PAST PRACTICE
INTRODUCTION QUANTIFY ROCK MASS RELATE TO PAST PRACTICE PREDICTION INTRODUCTION ANALYTICAL OBSERVATIONAL EMPIRICAL UBC MINING & MINERAL PROCESS ENGINEERING SAFETY & WORKABLE GEOMECHANICS DESIGN GROUP
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ROCK MASS STOPE DESIGN PILLAR DESIGN SPAN DESIGN SUPPORT STRESS 1998
STRUCTURE UBC MINING & MINERAL PROCESS ENGINEERING STRESS ROCK MASS 1998 GEOMECHANICS DESIGN GROUP
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STRESS INDUCED LOAD INPUT PARAMETERS GUESTIMATE
UBC MINING & MINERAL PROCESS ENGINEERING GEOMECHANICS DESIGN GROUP
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STRUCTURE GEOMETRY SHEAR STRENGTH SUPPORT GEOMECHANICS DESIGN GROUP
UBC MINING & MINERAL PROCESS ENGINEERING GEOMECHANICS DESIGN GROUP
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ROCK MASS CLASSIFICATION
RMR (1976) Q - SYSTEM (1974) UBC MINING & MINERAL PROCESS ENGINEERING GEOMECHANICS DESIGN GROUP
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STABILITY GRAPH (ELOS)
OPENING DESIGN STABILITY GRAPH (ELOS) CRITICAL SPAN CURVE
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ELOS – EQUIVALENT LINEAR OVERBREAK SLOUGH
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RELAXED HW A = 1 PARALLEL STRUCTURE B = 0.2, 0.3 WALL DIP C = ( 8 - 6*COS f )
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MODIFIED STABILITY GRAPH – RADIUS FACTOR
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RADIUS FACTOR = 1.1 X HYDRAULIC RADIUS
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STABILITY GRAPH (ELOS)
OPENING DESIGN STABILITY GRAPH (ELOS) CRITICAL SPAN CURVE
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SPAN DESIGN CURVE
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WEAK ROCK MASS SEISMICITY EXTENT OF FAILURE 6ft 5ft 10ft
( ) 6ft 10ft 3ft x 3ft BOLT SPACING (0.5*10ft*5ft*3ft)/11ft3/ton= 7ton 5ft
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PREDICTIVE TOOL SPAN ESTIMATION
3 3 1 292 CASE HISTORIES (160 STABLE, 59 POT, 73 UNSTABLE) 18 X 18 GRID - NEURAL OUTPUT (324 pts)
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PREDICTIVE TOOL SPAN ESTIMATION
NEURAL NET RESULTS IN CONTOUR PLOT OF 1=.100% STABLE TO 3=100% UNSTABLE TRAINING ERROR = 12%
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PILLAR DESIGN PILLAR LOAD/UCS PILLAR WIDTH/HEIGHT
UBC MINING & MINERAL PROCESS ENGINEERING GEOMECHANICS DESIGN GROUP
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PILLAR STABILITY GRAPH
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PILLAR STABILITY GRAPH
Wp/Hp < 1 SEISMICITY
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GOLDCORP RED LAKE MINE 1700m below surface 47g/tonne GOLD 600 TPD
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MEDIUM BURST POTENTIAL Pillar Stability Graph Induced Stress Criteria
BURST PRONE CRITERIA STABLE UNSTABLE FAILED LOW BURST POTENTIAL MEDIUM BURST POTENTIAL HIGH BURST POTENTIAL Pillar Stability Graph FS > 1.4 on Pillar Stability Graph 1.0 < FS < 1.4 FS<1.0 Induced Stress Criteria s 1/UCS < 0.5 0.5 < s 1/UCS < 0.6 s 1/UCS > 0.6 Pillar Geometry Wp/Hp > 3 2 < Wp/Hp < 3 Wp/Hp < 2 Observations Minor ground working, minor spalling Ground working, pillar spalling Substantial bursting * * in process of being evaluated - microseismic
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STUDY AT QUINSAM MINE – BRITISH COLUMBIA - CANADA
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SURFACE SUBSIDENCE OVER SHALLOW EXCAVATIONS
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ANGLE OF CRITICAL DEFORMATION IS <10o FROM VERTICAL
STRUCTURAL CONTROL DEPTH OF CAVE AS MUCH AS 14X EXCAVATION HEIGHT
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CONCLUSIONS CALIBRATION TO ANALYTICAL AND EMPIRICAL APPROACHES
INTERPOLATE, NOT EXTRAPOLATE KNOW THY DATABASE TOOL CALIBRATION TO ANALYTICAL AND EMPIRICAL APPROACHES MODIFIED ACCORDING TO MINE BEHAVIOUR UBC MINING & MINERAL PROCESS ENGINEERING SAFETY & WORKABLE GEOMECHANICS DESIGN GROUP
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ACKNOWLEDGEMENT NIOSH CERM3
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