Rock Mechanics: For underground mining

647 Pages·2006·25.477 MB·English

by  Barry H.G. Brady, E.T. Brown

Rock Mechanics
Frontispiece Post-pillarminingina
jointed and faulted rock mass at the
DolphinMine,KingIsland,Australia
(photographbypermissionofKingIs-
landScheeliteandCSIRODivisionof
Geomechanics).
Rock
Mechanics
for underground mining
Third edition
B. H. G. Brady
EmeritusProfessor,TheUniversityofWesternAustralia,andConsulting
Engineer,Montville,Queensland,Australia
E. T. Brown
EmeritusProfessor,TheUniversityofQueensland,andSeniorConsultant,
GolderAssociatesPtyLtd,Brisbane,Australia
KLUWER ACADEMIC PUBLISHERS
NEW YORK,BOSTON, DORDRECHT, LONDON, MOSCOW
eBookISBN: 1-4020-2116-X
Print ISBN: 1-4020-2064-3
©2005 Springer Science + Business Media, Inc.
Print ©1985, 1993, 2004 B.H.G. Brady and E.T. Brown
Dordrecht
All rights reserved
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Contents
Prefacetothethirdedition xi
Prefacetothesecondedition xiii
Prefacetothefirstedition xv
Acknowledgements xvii
1 Rockmechanicsandminingengineering 1
1.1 Generalconcepts 1
1.2 Inherentcomplexitiesinrockmechanics 4
1.3 Undergroundmining 6
1.4 Functionalinteractionsinmineengineering 9
1.5 Implementationofarockmechanicsprogramme 13
2 Stressandinfinitesimalstrain 17
2.1 Problemdefinition 17
2.2 Forceandstress 17
2.3 Stresstransformation 19
2.4 Principalstressesandstressinvariants 23
2.5 Differentialequationsofstaticequilibrium 25
2.6 Planeproblemsandbiaxialstress 26
2.7 Displacementandstrain 29
2.8 Principalstrains 33
2.9 Straincompatibilityequations 34
2.10 Stress-strainrelations 34
2.11 Cylindricalpolarco-ordinates 37
2.12 Geomechanicsconvention 39
2.13 Graphicalrepresentationofbiaxialstress 41
Problems 43
3 Rockmassstructureandcharacterisation 46
3.1 Introduction 46
3.2 Majortypesofstructuralfeatures 47
3.3 Importantgeomechanicalpropertiesofdiscontinuities 51
3.4 Collectingstructuraldata 57
3.5 Presentationofstructuraldata 69
3.6 Thehemisphericalprojection 71
3.7 Rockmassclassification 77
Problems 82
4 Rockstrengthanddeformability 85
4.1 Introduction 85
4.2 Conceptsanddefinitions 86
v
CONTENTS
4.3 Behaviourofisotropicrockmaterialinuniaxial
compression 87
4.4 Behaviourofisotropicrockmaterialinmultiaxial
compression 99
4.5 Strengthcriteriaforisotropicrockmaterial 105
4.6 Strengthofanisotropicrockmaterialintriaxialcompression 117
4.7 Shearbehaviourofdiscontinuities 120
4.8 Modelsofdiscontinuitystrengthanddeformation 130
4.9 Behaviourofdiscontinuousrockmasses 133
Problems 139
5 Pre-miningstateofstress 142
5.1 Specificationofthepre-miningstateofstress 142
5.2 Factorsinfluencingtheinsitustateofstress 143
5.3 Methodsofinsitustressdetermination 147
5.4 Presentationofinsitu stressmeasurementresults 156
5.5 Resultsofinsitustressmeasurements 159
Problems 161
6 Methodsofstressanalysis 165
6.1 Analyticalmethodsforminedesign 165
6.2 Principlesofclassicalstressanalysis 166
6.3 Closed-formsolutionsforsimpleexcavationshapes 173
6.4 Computationalmethodsofstressanalysis 178
6.5 Theboundaryelementmethod 179
6.6 Thefiniteelementmethod 183
6.7 Thedistinctelementmethod 189
6.8 Finitedifferencemethodsforcontinuousrock 192
6.9 Linkedcomputationalschemes 195
7 Excavationdesigninmassiveelasticrock 197
7.1 Generalprinciplesofexcavationdesign 197
7.2 Zoneofinfluenceofanexcavation 201
7.3 Effectofplanesofweaknessonelasticstressdistribution 204
7.4 Excavationshapeandboundarystresses 209
7.5 Delineationofzonesofrockfailure 213
7.6 Supportandreinforcementofmassiverock 217
Problems 221
8 Excavationdesigninstratifiedrock 224
8.1 Designfactors 224
8.2 Rockmassresponsetomining 225
8.3 Roofbeddeformationmechanics 227
8.4 Roofdesignprocedureforplanestrain 230
8.5 Roofbeamanalysisforlargeverticaldeflection 235
vi
CONTENTS
9 Excavationdesigninblockyrock 242
9.1 Designfactors 242
9.2 Identificationofpotentialblockfailuremodes–BlockTheory 243
9.3 Symmetrictriangularroofprism 255
9.4 Roofstabilityanalysisforatetrahedralblock 261
9.5 Designpracticeinblockyrock 263
9.6 Stopewalldesign–theMathewsstabilitychartmethod 266
10 Energy,minestability,mineseismicityandrockbursts 271
10.1 Mechanicalrelevanceofenergychanges 271
10.2 Miningconsequencesofenergychanges 275
10.3 Energytransmissioninrock 277
10.4 Sphericalcavityinahydrostaticstressfield 285
10.5 Generaldeterminationofreleasedandexcessenergy 289
10.6 Minestabilityandrockbursts 293
10.7 Instabilityduetopillarcrushing 294
10.8 Thintabularexcavations 299
10.9 Instabilityduetofaultslip 301
10.10 Characterisationofseismicevents 304
11 Rocksupportandreinforcement 312
11.1 Terminology 312
11.2 Supportandreinforcementprinciples 313
11.3 Rock–supportinteractionanalysis 317
11.4 Pre-reinforcement 322
11.5 Supportandreinforcementdesign 326
11.6 Materialsandtechniques 338
12 Miningmethodsandmethodselection 347
12.1 Miningexcavations 347
12.2 Rockmassresponsetostopingactivity 349
12.3 Orebodypropertiesinfluencingminingmethod 352
12.4 Undergroundminingmethods 355
12.5 Miningmethodselection 368
13 Pillarsupportedminingmethods 370
13.1 Componentsofasupportedminestructure 370
13.2 Fieldobservationsofpillarperformance 372
13.3 Elementaryanalysisofpillarsupport 375
13.4 Designofastope-and-pillarlayout 384
13.5 Bearingcapacityofroofandfloorrocks 390
13.6 TheElliotLakeroom-and-pillarmines 391
13.7 Stope-and-pillardesigninirregularorebodies 396
13.8 Openstope-and-pillardesignatMountCharlotte 403
vii
CONTENTS
13.9 Yieldingpillars 405
Problems 406
14 Artificiallysupportedminingmethods 408
14.1 Techniquesofartificialsupport 408
14.2 Backfillpropertiesandplacement 410
14.3 Designofminebackfill 416
14.4 Cut-and-fillstoping 419
14.5 Backfillapplicationsinopenandbenchstoping 423
14.6 Reinforcementofopenstopewalls 428
15 Longwallandcavingminingmethods 430
15.1 Classificationoflongwallandcavingminingmethods 430
15.2 Longwallmininginhardrock 430
15.3 Longwallcoalmining 440
15.4 Sublevelcaving 453
15.5 Blockcaving 465
Problems 481
16 Mining-inducedsurfacesubsidence 484
16.1 Typesandeffectsofmining-inducedsubsidence 484
16.2 Chimneycaving 486
16.3 Sinkholesincarbonaterocks 495
16.4 Discontinuoussubsidenceassociatedwithcaving
methodsofmining 496
16.5 Continuoussubsidenceduetotheminingof
tabularorebodies 506
17 Blastingmechanics 518
17.1 Blastingprocessesinundergroundmining 518
17.2 Explosives 518
17.3 Elasticmodelsofexplosive–rockinteraction 521
17.4 Phenomenologyofrockbreakagebyexplosives 522
17.5 Computationalmodelsofblasting 527
17.6 Perimeterblasting 527
17.7 Transientgroundmotion 532
17.8 Dynamicperformanceanddesignofundergroundexcavations 536
17.9 Evaluationofexplosiveandblastperformance 538
18 Monitoringrockmassperformance 543
18.1 Thepurposesandnatureofmonitoringrock
massperformance 543
18.2 Monitoringsystems 544
18.3 Examplesofmonitoringrockmassperformance 558
viii
CONTENTS
AppendixA Basicconstructionsusingthe
hemisphericalprojection 568
A.1 Projectionofaline 568
A.2 Projectionofthegreatcircleandpoletoaplane 568
A.3 Determinationofthelineofintersectionoftwoplanes 569
A.4 Determinationoftheanglebetweentwolinesinaplane 570
A.5 Determinationofdipdirectionandtruedip 571
A.6 Rotationaboutaninclinedaxis 572
Appendix B Stresses and displacements induced by point and
infinitelineloadsinaninfinite,isotropic,elasticcontinuum 574
B.1 Apointload(theKelvinequations) 574
B.2 Aninfinitelineload 575
AppendixC Calculationsequencesforrock–support
interactionanalysis 575
C.1 Scope 575
C.2 Requiredsupportlinecalculations 575
C.3 Availablesupportlinecalculations 577
AppendixD Limitingequilibriumanalysisofprogressive
hangingwallcaving 580
D.1 Derivationofequations 580
D.2 Calculationsequence 584
Answerstoproblems 585
References 589
Index 614
ix