Rock mechanics for underground mining, 3rd ed $Z[W}7{pt#
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by t?;\'
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B. H. G. Brady 8m"jd+
Emeritus Professor, The University of Western Australia, and Consulting $v0beN6MG
Engineer, Montville, Queensland, Australia _fE$KaP
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E. T. Brown l#cG#-
Emeritus Professor, The University of Queensland, and Senior Consultant, %8$ldNhV
Golder Associates Pty Ltd, Brisbane, Australia \zM3{{mV/
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KLUWER ACADEMIC PUBLISHERS 4"~l^yK
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2005 Springer Science + Business Media, Inc c01i!XS
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Preface to the third edition bTbF
Sometimes it is suggested that mining engineering and its supporting engineering 32x[6"T
sciences have reached a state of maturity. However, this proposition is inconsistent hG8<@
with major developments in the twenty years that have elapsed since the preparation of 83g$k
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the first edition of this book, and the ten years since it has been subject to any substantial g=L80$1
revision. Over those periods, innovations and improvements in engineering practice >Pf\"%*
in mining and mining rock mechanics, and advances in the engineering science of iM(Q-%HP_
rock mechanics, have been extraordinary. For these reasons the third edition, which z6x`O-\
results from comprehensive and thorough revision of the earlier editions, has involved 35/K9l5
the replacement or substantial modification of the equivalent of about half of the text "'v^X!"
and figures of those versions of the book. Td,s"p>Vq
One of the key drivers for many significant developments in fundamental rock mechanics bd)'1;p
over the period has been the mining industry’s recognition of the economic L5 Q^cY]p
returns of better understanding and more rigorous application of the governing sciences jHQnD]Hr
embedded in its industrial operations and processes. The result has been some j`:D BO&)\
notable advances in mining engineering practice, involving improvements in mining DuI>z?bS
methods in particular. For example, caving methods are now more widely applied ckdXla
as understanding of their scientific basis has improved and their economic and operational ~>B`T%=H
advantages have been realised. Whereas sublevel caving was once regarded Qs\*r@6?
in some places as a method of marginal interest, the advent of very large scale sublevel PB?92py&
caving, made possible in part by improved drilling technology and in part by nR`)kORc
understanding of the governing rock mechanics, it is now an attractive proposition for Df5!z \dx
many orebodies. Similarly, block caving is now conducted efficiently and reliably in =>htX(k}
orebody settings that would have been inconceivable two decades ago. At the same ?'RB'o~
time, methods such as overhand cut-and-fill stoping and shrink stoping have declined r<c&;*
in application, replaced in part by open stoping and bench-and-fill stoping, where large P87Lo4Rd
scale mechanisation, improved backfill technology, reliable rock mass reinforcement xZ(ryE%
of stope walls and the intrinsic advantages of non-entry methods of working have led }BI|M_q.1~
to superior economics and enhanced operational safety. #6*20w_u
The scope of developments in mining rock mechanics science and practice has been E_-QGE/1
as impressive as that in mining engineering. Perhaps the most significant advance has P^[y~I#{
been the resolution of some longstanding issues of rock fracture, failure and strength _bn
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and their relation to the modes of deformation and degradation of rock around mining 14z
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excavations. The fact that the key research on this topic was conducted at the Underground Ge1b_?L_
Research Laboratory of Atomic Energy of Canada Limited demonstrates the uZe"M(3r$
extent to which mining rock mechanics has benefited from fundamental research in Ld?'X=eQ
other fields of rock engineering. The mechanics of blocky rock has also been a field of yZQcxg%
impressive development, particularly in regard to formulation of a broad spectrum of o1Nfn'!3/>
methods of analysis of block jointed rock and their application in excavation engineering Y1R?,5
and support and reinforcement design. More generally, improved understanding Z]08gH
of the mechanics of discontinuous rock has had a profound effect on simulation of 9Yd"Y-
caving mechanics and therefore on the design and operation of block caving and mnL+@mm
sublevel caving mines. :JIJ!Xn)
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Mining-induced seismicity and the related phenomenon of rockbursts have become zEk/15
more prevalent in hard rock mining. Developments in mineworthy seismic equipment SW)jDy
and associated data recording, processing and analysis hardware and software have ve^gzE$<I
contributed greatly to measurement, characterisation and management of the problem. yS1i$[JV
These developments have been complemented by measures in excavation design YF)k0bu&;
and extraction sequencing which have done much to mitigate the serious operating apZPHau6h
problems which can occur in seismically active, rockburst prone mines. In large-scale }inV)QQ
open stope mining, Canadian developments based on pillarless stoping, formulation C`qE ,2.
of extraction sequences which promote the evolution and uniform displacement of a %U6A"?To
regular mine stress abutment, and the extensive use of cement-stabilised backfill, have DIw9ov>k
been successful in managing an acute mining challenge. Notably, these measures have \![ p-mW{
been based on sound conceptual and analytical models of the relation of damaging l1vI
seismicity to induced stress, geological structure, potential rock displacements and 6u>]-K5
strain energy release during mining. +E-CsNAZ*"
Some remarkable developments in computational methods have supported these o[)*Y`xq<w
improvements in rock mechanics practice. Many mining rock mechanics problems Y.kgJ #2
are effectively four-dimensional, in that it is the evolution of the state of stress over the 0Ua&_D"
time scale of the mining life of the orebody which needs to be interpreted in terms of nrg$V>pD
the probable modes of response of the host rock mass. The computational efficiency "p]!="\
of tools for three-dimensional stress analysis now permits modelling of key stages of bs0[ a 1/
an extraction sequence, for example, as a matter of routine rock mechanics practice. xauMF~*
Similarly, computer power and efficient algorithms provide a notable capacity to QJ +Ml
simulate the displacement and flow of rock in cave mining and to support design of U^8S@#1Q
optimum caving layouts. K<q#2G0{
Notwithstanding these developments, it is encouraging to note continued attention A DVUx}
to formal mathematical analysis in solution of rock mechanics problems. The results yw1-4*$c
of such analysis provide the canonical solutions for the discipline of rock mechanics xVk5%
and ensure a sound base for both the science and engineering practice. |y
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In preparing this extensive revision, the authors have been fortunate to have the 72 ZoN<c
support of many colleagues and several organisations. In particular, they would like i>O8q%BnJ
to record the helpful advice and comment of colleagues on possible improvements jN-!1O._G
in earlier editions of the book and in identifying inevitable errors in the text. They AQwai>eL
acknowledge the generous assistance of the Brisbane office of Golder Associates in P^AI*tH"m
providing facilities and many helpful services, particularly in assistance with drafting SHT`
of the figures for this edition. One of the authors was supported for part of the 8SA"
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work of revision by The University of Western Australia, and the other by the Julius ?Wc+
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Kruttschnitt Mineral Research Centre of The University of Queensland. This support, 9oYE
including the associated library services, is acknowledged with gratitude. The authors +kN,OK~
thank the many individuals and organisations who generously gave permission to use 'xLXj>
published material. Finally, they record the encouragement of publisher’s representative, =0az5td
Petra van Steenbergen, and her patient assistance and advice during this major WK0:3q(P
undertaking. !
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B. H. G. B. ?|~KF:,#}
E. T. B. _y&XFdp
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