Rock Mechanics.pdf - Mining and Blasting

More documents

Recommendations

Info

STOPE-AND-PILLAR DESIGN IN IRREGULAR OREBODIES An obvious mining objective in developing an extraction sequence is to assure recovery of the highest grade blocks in the orebody. While this is not to suggest that a strategy of ‘high grading’ should be pursued, the requirement is to extract the high grade blocks completely, in order to maximise mineral yield. Maximising mineral yield can be coupled to the geomechanics requirement to establish a mining sequence which provides predictable behaviour of the mine layout, particularly under conditions of an increasing volume of rock mass degradation as mining proceeds. From a geomechanics perspective, the overall sequence should involve the early extraction of blocks with little support potential; avoiding leaving scattered pillar remnants; where essential, leaving bracket pillars to control displacements on major structural features; and orderly retreat of mining towards stable or solid ground. These guidelines were proposed from experience in mines achieving a high extraction ratio or under challenging conditions of pre-mining states of stress. Some instructive background is provided by South African mining practice in deep, tabular orebodies (COMRO, 1998), where the use of bracket pillars at fault intersections with the orebody, the use of mine-scale stabilising pillars and the necessity of orderly advance towards the mine abutments is well demonstrated. However, it should be noted that high pre-mining stresses are not the driver for a properly engineered extraction sequence. Even for mines located in a benign stress field, it is possible to lose a considerable proportion of the ore reserve through a poorly conceived extraction sequence. Starting from the structural geology and a capacity to model the evolving stress distribution in an extraction layout, an extraction sequence is defined by identification of an initial point of attack in the orebody, a logical evolution of the stope and pillar layout and an unambiguous order for pillar extraction. This is frequently possible in a single orebody mined in a planar layout. For the case of multiple orebodies or a large orebody mined in a three-dimensional structure of stopes and pillars, it is sometimes difficult to identify the optimum extraction sequence. It is usually necessary to propose several extraction sequences which satisfy production scheduling and other mine engineering requirements such as access and ventilation, and also involve the maintenance of an orderly direction of retreat of stoping towards stable ground. The preferred sequence may be established by analysis of rock response for each extraction scheme, comparing the evolution of states of stress and rock mass conditions for each of the alternatives, using the techniques described earlier due to Diederichs et al. (2002). Extraction sequencing is a key aspect of control of mine instability and seismicity. As discussed by Morrison (1996), the stope and pillar layout illustrated in Figure 13.29a, based on primary stoping of each second ore block recovery of the pillars in secondary stopes, has many advantages in terms of controlling ground displacements in the initial stages of mining. However, under conditions of high stress and active seismicity, pillar recovery in secondary stopes can present challenging ground control problems. Many mines in such settings use the pillarless, centre-out stoping sequence shown in Figure 13.29b, usually employing cemented backfill to limit the unsupported spans of stope walls. Maintenance of the ‘chevron’ front for advance of stoping has a particular advantage in that it promotes the development of a geometrically regular stress abutment adjacent to the stoping front. The stress abutment is displaced incrementally and uniformly with the advance of the stoping front and stope wall 401
Figure 13.29 (a) Stope and pillar layout for an extraction sequence based on primary stoping and pillar recovery in secondary stopes. The ‘1-3-5’ sequence involves primary stoping of each second ore block. (b) Pillarless mining sequence in which ore blocks are mined to maintain a ‘chevron’ mining front (after Morrison, 1996). Figure 13.30 Three-dimensional representation of the pyramidal pillarless mining sequence at the Brunswick Mine (after Andrieux and Simser, 2001). PILLAR SUPPORTED MINING METHODS convergence behind the advancing face is relatively uniform. According to Morrison (1996), although the sequence does not eliminate large seismic events and associated rockbursts, it can significantly reduce the magnitudes of such events. An interesting example of sequencing of extraction in a complex mining geometry is provided by Andrieux and Simser (2001). The Brunswick Mine is characterised by states of stress which lead to damaging seismicity and rock structure which poses instability problems in zones of stress reduction. In two dimensions, the extraction sequence resembles one half of the chevron pattern illustrated in Figure 13.29. The stopes are mined ‘en-echelon’, by pillarless stoping, with overall progression of stoping towards the final abutments for the extracted orebody. In three dimensions, the orderly displacement of the abutment stress is provided by a sequence called pyramidal pillarless mining, as illustrated in Figure 13.30. Implementation of the sequence 402
Page 1 and 2:
Rock Mechanics
Page 3 and 4:
Rock Mechanics for underground mini
Page 5 and 6:
Contents Preface to the third editi
Page 7 and 8:
CONTENTS 9 Excavation design in blo
Page 9 and 10:
CONTENTS ix Appendix A Basic constr
Page 11 and 12:
PREFACE TO THE THIRD EDITION Mining
Page 13 and 14:
PREFACE TO THE SECOND EDITION In th
Page 15 and 16:
PREFACE TO THE FIRST EDITION design
Page 17 and 18:
ACKNOWLEDGEMENTS Safety in Mines Re
Page 19 and 20:
Figure 1.1 (a) Pre-mining condition
Page 21 and 22:
ROCK MECHANICS AND MINING ENGINEERI
Page 23 and 24:
Page 25 and 26:
Figure 1.4 Principal features of a
Page 27 and 28:
10 Figure 1.5 Definition of activit
Page 29 and 30:
Page 31 and 32:
Figure 1.7 Components and logic of
Page 33 and 34:
Page 35 and 36:
Figure 2.1 (a) A finite body subjec
Page 37 and 38:
Figure 2.2 Free-body diagram for es
Page 39 and 40:
STRESS AND INFINITESIMAL STRAIN As
Page 41 and 42:
STRESS AND INFINITESIMAL STRAIN In
Page 43 and 44:
Figure 2.3 Free-body diagram for de
Page 45 and 46:
Figure 2.5 Problem geometry for det
Page 47 and 48:
Figure 2.7 Rigid-body rotation of a
Page 49 and 50:
STRESS AND INFINITESIMAL STRAIN the
Page 51 and 52:
STRESS AND INFINITESIMAL STRAIN str
Page 53 and 54:
⎡ ⎢ ⎣ xx yy zz xy yz zx STRES
Page 55 and 56:
Figure 2.11 Cylindrical polar coord
Page 57 and 58:
STRESS AND INFINITESIMAL STRAIN fre
Page 59 and 60:
Figure 2.13 Construction of a Mohr
Page 61 and 62:
STRESS AND INFINITESIMAL STRAIN fun
Page 63 and 64:
3 Rock Figure 3.1 Sidewall failure
Page 65 and 66:
Figure 3.2 Jointing in a folded str
Page 67 and 68:
Figure 3.5 Diagrammatic longitudina
Page 69 and 70:
Figure 3.7 Discontinuity spacing hi
Page 71 and 72:
Figure 3.9 Illustration of persiste
Page 73 and 74:
Figure 3.11 Typical roughness profi
Page 75 and 76:
ROCK MASS STRUCTURE AND CHARACTERIS
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Figure 3.17 Sample number vs. preci
Page 83 and 84:
Figure 3.19 Diagrammatic illustrati
Page 85 and 86:
Page 87 and 88:
Figure 3.20 Computerised depiction
Page 89 and 90:
Figure 3.23 Stereographic projectio
Page 91 and 92:
Figure 3.26 Polar stereographic net
Page 93 and 94:
Figure 3.28 Contours of pole concen
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Figure 3.30 Geological Strength Ind
Page 101 and 102:
Page 103 and 104:
Figure 4.1 Idealised illustration o
Page 105 and 106:
ROCK STRENGTH AND DEFORMABILITY wit
Page 107 and 108:
Figure 4.4 Influence of end restrai
Page 109 and 110:
ROCK STRENGTH AND DEFORMABILITY whe
Page 111 and 112:
Figure 4.8 Principle of closed-loop
Page 113 and 114:
Figure 4.12 Two classes of stress-
Page 115 and 116:
Figure 4.14 Point load test apparat
Page 117 and 118:
Figure 4.15 Biaxial compression tes
Page 119 and 120:
Figure 4.18 Results of triaxial com
Page 121 and 122:
ROCK STRENGTH AND DEFORMABILITY was
Page 123 and 124:
Figure 4.23 Coulomb strength envelo
Page 125 and 126:
Figure 4.25 Extension of a preexist
Page 127 and 128:
Figure 4.29 The three basic modes o
Page 129 and 130:
Figure 4.30 Normalised peak strengt
Page 131 and 132:
ROCK STRENGTH AND DEFORMABILITY Tab
Page 133 and 134:
Figure 4.32 The normality condition
Page 135 and 136:
Figure 4.33 Variation of peak princ
Page 137 and 138:
Figure 4.35 Direct shear test confi
Page 139 and 140:
Figure 4.37 Shear stress-shear disp
Page 141 and 142:
Figure 4.40 Peak and residual effec
Page 143 and 144:
Figure 4.43 Effect of shearing dire
Page 145 and 146:
Figure 4.45 Relations between norma
Page 147 and 148:
Figure 4.47 Coulomb friction, linea
Page 149 and 150:
ROCK STRENGTH AND DEFORMABILITY whe
Page 151 and 152:
Figure 4.49 Composite peak strength
Page 153 and 154:
Figure 4.50 Hoek-Brown peak strengt
Page 155 and 156:
Figure 4.52 Determination of the Yo
Page 157 and 158:
ROCK STRENGTH AND DEFORMABILITY 4 A
Page 159 and 160:
5 Pre-mining Figure 5.1 Method of s
Page 161 and 162:
Figure 5.2 The effect of irregular
Page 163 and 164:
PRE-MINING STATE OF STRESS surround
Page 165 and 166:
PRE-MINING STATE OF STRESS induced
Page 167 and 168:
Figure 5.5 (a) Definition of hole l
Page 169 and 170:
Figure 5.6 (a) Core drilling a slot
Page 171 and 172:
Figure 5.7 Principles of stress mea
Page 173 and 174:
PRE-MINING STATE OF STRESS strength
Page 175 and 176:
PRE-MINING STATE OF STRESS A second
Page 177 and 178:
PRE-MINING STATE OF STRESS by the e
Page 179 and 180:
PRE-MINING STATE OF STRESS extend i
Page 181 and 182:
PRE-MINING STATE OF STRESS (d) Dete
Page 183 and 184:
METHODS OF STRESS ANALYSIS quantita
Page 185 and 186:
METHODS OF STRESS ANALYSIS It is in
Page 187 and 188:
Figure 6.2 A thick-walled cylinder
Page 189 and 190:
METHODS OF STRESS ANALYSIS For the
Page 191 and 192:
Figure 6.3 Problem geometry, coordi
Page 193 and 194:
Figure 6.4 Problem geometry, coordi
Page 195 and 196:
METHODS OF STRESS ANALYSIS When the
Page 197 and 198:
Figure 6.5 Superposition scheme dem
Page 199 and 200:
METHODS OF STRESS ANALYSIS The disc
Page 201 and 202:
Figure 6.7 Development of a finite
Page 203 and 204:
METHODS OF STRESS ANALYSIS Solution
Page 205 and 206:
Figure 6.8 A simple finite element
Page 207 and 208:
Figure 6.9 A schematic representati
Page 209 and 210:
METHODS OF STRESS ANALYSIS block ce
Page 211 and 212:
METHODS OF STRESS ANALYSIS where ˚
Page 213 and 214:
METHODS OF STRESS ANALYSIS The prin
Page 215 and 216:
EXCAVATION DESIGN IN MASSIVE ELASTI
Page 217 and 218:
Figure 7.2 A logical framework for
Page 219 and 220:
Figure 7.3 (a) Axisymmetric stress
Page 221 and 222:
Figure 7.6 A plane of weakness, ori
Page 223 and 224:
Figure 7.8 A flat-lying plane of we
Page 225 and 226:
Figure 7.10 Shear stress/normal str
Page 227 and 228:
Figure 7.12 Ovaloidal opening in a
Page 229 and 230:
Figure 7.15 States of stress at sel
Page 231 and 232:
Figure 7.16 Prediction of the exten
Page 233 and 234:
Figure 7.18 Contour plots of princi
Page 235 and 236:
Figure 7.19 Problem geometry for de
Page 237 and 238:
Page 239 and 240:
Page 241 and 242:
8 Excavation Figure 8.1 An excavati
Page 243 and 244:
EXCAVATION DESIGN IN STRATIFIED ROC
Page 245 and 246:
Figure 8.4 Experimental apparatus f
Page 247 and 248:
Figure 8.7 Free body diagrams and n
Page 249 and 250:
Figure 8.8 Assumed distributions of
Page 251 and 252:
Figure 8.9 Flow chart for the deter
Page 253 and 254:
Figure 8.10 Normalised arch thickne
Page 255 and 256:
EXCAVATION DESIGN IN STRATIFIED ROC
Page 257 and 258:
Figure 8.11 Normalised deflection a
Page 259 and 260:
9 Excavation Figure 9.1 Generation
Page 261 and 262:
Figure 9.3 (a) A finite, non-tapere
Page 263 and 264:
(a) (b) Figure 9.4 (a) Vertical cro
Page 265 and 266:
(a) (b) (c) EP EP Reference circle
Page 267 and 268:
Figure 9.10 JP 100 is the only JP w
Page 269 and 270:
Figure 9.12 Traces of the views of
Page 271 and 272:
EXCAVATION DESIGN IN BLOCKY ROCK In
Page 273 and 274:
Figure 9.14 Free-body diagrams of a
Page 275 and 276:
EXCAVATION DESIGN IN BLOCKY ROCK di
Page 277 and 278:
Figure 9.16 Symmetrical wedge in th
Page 279 and 280:
Figure 9.17 (a) Geometry for determ
Page 281 and 282:
Figure 9.18 Problem geometry demons
Page 283 and 284:
Figure 9.20 Cut-and-fill stope mine
Page 285 and 286:
Figure 9.22 Chart to determine fact
Page 287 and 288:
EXCAVATION DESIGN IN BLOCKY ROCK Th
Page 289 and 290:
Figure 10.1 (a) Pre-mining state of
Page 291 and 292:
Figure 10.3 (a) Dynamic loading of
Page 293 and 294:
Figure 10.5 (a) Pre-mining and (b)
Page 295 and 296:
Figure 10.6 Problem definition and
Page 297 and 298:
ENERGY, MINE STABILITY, MINE SEISMI
Page 299 and 300:
Figure 10.9 Force and stress compon
Page 301 and 302:
Page 303 and 304:
Page 305 and 306:
Page 307 and 308:
Figure 10.12 Distribution of radial
Page 309 and 310:
Figure 10.15 Problem geometry for d
Page 311 and 312:
Figure 10.17 (a) Schematic represen
Page 313 and 314:
Page 315 and 316:
Figure 10.20 Elastic/post-peak stif
Page 317 and 318:
Page 319 and 320:
Figure 10.24 Relation between frequ
Page 321 and 322:
Page 323 and 324:
Page 325 and 326:
Figure 10.28 Six possible ways that
Page 327 and 328:
Figure 10.29 First motions for P an
Page 329 and 330:
11Rock support and reinforcement 11
Page 331 and 332:
Figure 11.1 (a) Hypothetical exampl
Page 333 and 334:
Figure 11.4 Non-linear support reac
Page 335 and 336:
Figure 11.5 Idealised elastic-britt
Page 337 and 338:
Figure 11.6 Calculated required sup
Page 339 and 340:
ROCK SUPPORT AND REINFORCEMENT The
Page 341 and 342:
Figure 11.9 Ground reaction curves
Page 343 and 344:
Figure 11.12 Use of grouted reinfor
Page 345 and 346:
ROCK SUPPORT AND REINFORCEMENT If,
Page 347 and 348:
Figure 11.16 Local reinforcement ac
Page 349 and 350:
Figure 11.18 Typical working sketch
Page 351 and 352:
Figure 11.19 Permanent support and
Page 353 and 354:
Figure 11.22 Basis of natural coord
Page 355 and 356:
Figure 11.24 Distributions of (a) s
Page 357 and 358:
Figure 11.26 Resin grouted rockbolt
Page 359 and 360:
Figure 11.28 Alternative methods of
Page 361 and 362:
ROCK SUPPORT AND REINFORCEMENT Tabl
Page 363 and 364:
Figure 11.31 Toussaint-Heintzmann y
Page 365 and 366:
MINING METHODS AND METHOD SELECTION
Page 367 and 368: Figure 12.2 Elements of a supported
Page 369 and 370: MINING METHODS AND METHOD SELECTION
Page 375 and 376: Figure 12.6 Schematic layout for bi
Page 377 and 378: Figure 12.8 Layout for shrink stopi
Page 379 and 380: Figure 12.9 Schematic layout for VC
Page 381 and 382: Figure 12.11 Key elements of longwa
Page 383 and 384: Figure 12.13 Mining layout for tran
Page 387 and 388: 13 Figure 13.1 Schematic illustrati
Page 389 and 390: Figure 13.3 Layout of barrier pilla
Page 391 and 392: Figure 13.5 Principal modes of defo
Page 393 and 394: Figure 13.8 Geometry for tributary
Page 395 and 396: PILLAR SUPPORTED MINING METHODS str
Page 397 and 398: Figure 13.10 Distribution of vertic
Page 399 and 400: Figure 13.12 Pillar behaviour domai
Page 401 and 402: PILLAR SUPPORTED MINING METHODS Lun
Page 403 and 404: Figure 13.15 Options in the design
Page 405 and 406: Figure 13.17 Relation between yield
Page 407 and 408: Figure 13.19 Model of yield of coun
Page 409 and 410: Figure 13.20 North-south vertical c
Page 411 and 412: Figure 13.23 Stope-and-pillar layou
Page 413 and 414: Figure 13.25 Calibrated stability c
Page 415 and 416: PILLAR SUPPORTED MINING METHODS wor
Page 417: Figure 13.28 Pillar performance, de
Page 421 and 422: Figure 13.31 (a) Plane strain analy
Page 423 and 424: PILLAR SUPPORTED MINING METHODS Pan
Page 425 and 426: 14 Artificially supported mining me
Page 427 and 428: ARTIFICIALLY SUPPORTED MINING METHO
Page 431 and 432: Figure 14.2 Simplified view of stru
Page 435 and 436: Figure 14.5 Confined block model fo
Page 437 and 438: Figure 14.7 Crown and sidewall stre
Page 443 and 444: Figure 14.10 Sublevel open stoping
Page 445 and 446: Figure 14.12 Some applications of c
Page 447 and 448: 15 Longwall and caving mining metho
Page 449 and 450: Figure 15.2 Shear stress drop in th
Page 451 and 452: LONGWALL AND CAVING MINING METHODS
Page 453 and 454: LONGWALL AND CAVING MINING METHODS
Page 455 and 456: Figure 15.6 Hydraulic prop reaction
Page 457 and 458: Figure 15.7 Development and extract
Page 459 and 460: Figure 15.8 Vertical stress redistr
Page 461 and 462: Figure 15.11 Distribution of observ
Page 463 and 464: Figure 15.13 Plan view of microseis
Page 465 and 466: Figure 15.16 Ground-support interac
Page 467 and 468: Figure 15.18 Roadway support and re
Page 469 and 470:
LONGWALL AND CAVING MINING METHODS
Page 471 and 472:
Page 473 and 474:
Page 475 and 476:
Figure 15.25 Comparison of isolated
Page 477 and 478:
Figure 15.26 Geometry of a sublevel
Page 479 and 480:
Figure 15.28 Theoretical determinat
Page 481 and 482:
Figure 15.31 Deterioration of a cro
Page 483 and 484:
Figure 15.32 Distinct element simul
Page 485 and 486:
Page 487 and 488:
Figure 15.34 Extended Mathews stabi
Page 489 and 490:
Figure 15.36 Comparison of postand
Page 491 and 492:
Page 493 and 494:
Figure 15.39 Idealised plan illustr
Page 495 and 496:
Figure 15.41 Idealised vertical sec
Page 497 and 498:
Figure 15.42 Vertical slice through
Page 499 and 500:
Page 501 and 502:
16 Figure 16.1 Trough subsidence ov
Page 503 and 504:
MINING-INDUCED SURFACE SUBSIDENCE c
Page 505 and 506:
Figure 16.4 North-south section, At
Page 507 and 508:
Figure 16.6 (a) Rectangular block g
Page 509 and 510:
MINING-INDUCED SURFACE SUBSIDENCE f
Page 511 and 512:
Figure 16.8 Relation between stope
Page 513 and 514:
MINING-INDUCED SURFACE SUBSIDENCE M
Page 515 and 516:
MINING-INDUCED SURFACE SUBSIDENCE
Page 517 and 518:
Figure 16.14 Chart developed to est
Page 519 and 520:
Figure 16.16 Progressive hangingwal
Page 521 and 522:
Figure 16.19 Idealised model used i
Page 523 and 524:
Figure 16.21 Longitudinal section,
Page 525 and 526:
MINING-INDUCED SURFACE SUBSIDENCE t
Page 527 and 528:
MINING-INDUCED SURFACE SUBSIDENCE w
Page 529 and 530:
MINING-INDUCED SURFACE SUBSIDENCE F
Page 531 and 532:
Figure 16.25 Subsidence troughs pre
Page 533 and 534:
Figure 16.28 Predicted and measured
Page 535 and 536:
17 Blasting mechanics 17.1 Blasting
Page 537 and 538:
Figure 17.1 An empirical matching o
Page 539 and 540:
Figure 17.2 A finite difference mod
Page 541 and 542:
Figure 17.4 Reflection of a cylindr
Page 543 and 544:
BLASTING MECHANICS means that no ci
Page 545 and 546:
Figure 17.8 Layout of blast holes i
Page 547 and 548:
Figure 17.9 Influence of field stat
Page 549 and 550:
Figure 17.11 Generation of surface
Page 551 and 552:
BLASTING MECHANICS The components o
Page 553 and 554:
BLASTING MECHANICS amplitudes of th
Page 555 and 556:
BLASTING MECHANICS 17.9 Evaluation
Page 557 and 558:
Figure 17.15 (a) Schematic cross se
Page 559 and 560:
BLASTING MECHANICS in Figure 17.17,
Page 561 and 562:
MONITORING ROCK MASS PERFORMANCE (a
Page 563 and 564:
MONITORING ROCK MASS PERFORMANCE su
Page 565 and 566:
MONITORING ROCK MASS PERFORMANCE Ta
Page 567 and 568:
Figure 18.2 The Distometer ISETH, a
Page 569 and 570:
Figure 18.5 Self-inductance multipl
Page 571 and 572:
MONITORING ROCK MASS PERFORMANCE is
Page 573 and 574:
Figure 18.9 Biaxial vibrating wire
Page 575 and 576:
MONITORING ROCK MASS PERFORMANCE me
Page 577 and 578:
Figure 18.12 Cross section at 6650N
Page 579 and 580:
Figure 18.13 Examples of convergenc
Page 581 and 582:
Figure 18.15 Longitudinal section l
Page 583 and 584:
Figure 18.16 (Cont.) MONITORING ROC
Page 585 and 586:
Appendix A Basic constructions usin
Page 587 and 588:
Figure A.3 Determining the angle be
Page 589 and 590:
APPENDIX A USE OF HEMISPHERICAL PRO
Page 591 and 592:
APPENDIX B STRESSES AND DISPLACEMEN
Page 593 and 594:
Figure A.6 Axisymmetric tunnel prob
Page 595 and 596:
Figure A.9 Bolt load-extension curv
Page 597 and 598:
APPENDIX D LIMITING EQUILIBRIUM ANA
Page 599 and 600:
Page 601 and 602:
Page 603 and 604:
ANSWERS TO PROBLEMS 2 (a) 0.087 - 0
Page 605 and 606:
ANSWERS TO PROBLEMS 3 wp = 38.6 m,
Page 607 and 608:
REFERENCES Symp. & 17th Tunn. Assn
Page 609 and 610:
REFERENCES Brady, B. H. G. and Bray
Page 611 and 612:
REFERENCES Collier, P. A. (1993) De
Page 613 and 614:
REFERENCES Drescher, A. and Vardoul
Page 615 and 616:
REFERENCES Gustafsson, P. (1998) Wa
Page 617 and 618:
REFERENCES Hood, M. and Brown, E. T
Page 619 and 620:
REFERENCES Kaiser, P. K. and Tannan
Page 621 and 622:
REFERENCES Lorig, L. J. and Brady,
Page 623 and 624:
REFERENCES Ortlepp, W. D. (1994) Gr
Page 625 and 626:
REFERENCES Rojas, E., Molina, R. an
Page 627 and 628:
REFERENCES Spottiswoode, S. M. and
Page 629 and 630:
REFERENCES Villaescusa, E., Windsor
Page 631 and 632:
Index Page numbers appearing in bol
Page 633 and 634:
INDEX Coulomb (cont.) parameters 96
Page 635 and 636:
INDEX Excavation (cont.) support ra
Page 637 and 638:
INDEX Jaeger’s plane of weakness
Page 639 and 640:
INDEX Panel caving 470-2, 473, 474,
Page 641 and 642:
INDEX Seismic (cont.) moment 306, 3
Page 643 and 644:
INDEX Strength (cont.) residual 86,
Page 645:
INDEX United States (USA) 395, 396,
show all

Rock Mechanics.pdf - Mining and Blasting

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?