Rock mechanics for underground mining, 3rd ed 6%bZZTP`
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by U.]5UP:a
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B. H. G. Brady .?T,>#R
Emeritus Professor, The University of Western Australia, and Consulting F!DDlYUz.
Engineer, Montville, Queensland, Australia 6)i4&
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E. T. Brown c++GnQc.
Emeritus Professor, The University of Queensland, and Senior Consultant, qdkhfm2(K
Golder Associates Pty Ltd, Brisbane, Australia HriY-=ji>a
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KLUWER ACADEMIC PUBLISHERS :.wR *E
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2005 Springer Science + Business Media, Inc FCL7Tn
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Preface to the third edition &)[?D<
Sometimes it is suggested that mining engineering and its supporting engineering ]X
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sciences have reached a state of maturity. However, this proposition is inconsistent N>kY$ *
with major developments in the twenty years that have elapsed since the preparation of
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the first edition of this book, and the ten years since it has been subject to any substantial f]Jn\7j4
revision. Over those periods, innovations and improvements in engineering practice {cmY`to
in mining and mining rock mechanics, and advances in the engineering science of H9}z0VI
rock mechanics, have been extraordinary. For these reasons the third edition, which a *?bnw?
results from comprehensive and thorough revision of the earlier editions, has involved ;}v#hKC~
the replacement or substantial modification of the equivalent of about half of the text nBw4YDR!
and figures of those versions of the book. Ws%@SK
One of the key drivers for many significant developments in fundamental rock mechanics {~J'J $hn8
over the period has been the mining industry’s recognition of the economic :.8@ xVH
returns of better understanding and more rigorous application of the governing sciences w<=?%+n
embedded in its industrial operations and processes. The result has been some q<.m@q
notable advances in mining engineering practice, involving improvements in mining -]$q8Q(hM
methods in particular. For example, caving methods are now more widely applied YJdM6
as understanding of their scientific basis has improved and their economic and operational "Sm'TZx
advantages have been realised. Whereas sublevel caving was once regarded 72uARF
in some places as a method of marginal interest, the advent of very large scale sublevel xNlxi
caving, made possible in part by improved drilling technology and in part by KE>|,Ur
understanding of the governing rock mechanics, it is now an attractive proposition for {nvF>
many orebodies. Similarly, block caving is now conducted efficiently and reliably in v_M-:e3`
orebody settings that would have been inconceivable two decades ago. At the same |>_e&}Y%L
time, methods such as overhand cut-and-fill stoping and shrink stoping have declined xQLVFgd
in application, replaced in part by open stoping and bench-and-fill stoping, where large oYOR%'0*m+
scale mechanisation, improved backfill technology, reliable rock mass reinforcement m'{gO9V
of stope walls and the intrinsic advantages of non-entry methods of working have led T1,Nb>gBq^
to superior economics and enhanced operational safety. jeb]3i=pw
The scope of developments in mining rock mechanics science and practice has been m)"gj**|y
as impressive as that in mining engineering. Perhaps the most significant advance has ]-ad\PI$
been the resolution of some longstanding issues of rock fracture, failure and strength >&pB&'A a
and their relation to the modes of deformation and degradation of rock around mining c>I(6$
excavations. The fact that the key research on this topic was conducted at the Underground }8
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Research Laboratory of Atomic Energy of Canada Limited demonstrates the 6Ih8~Hu
extent to which mining rock mechanics has benefited from fundamental research in T<:mG%Is
other fields of rock engineering. The mechanics of blocky rock has also been a field of g{|F<2rd[m
impressive development, particularly in regard to formulation of a broad spectrum of 9e5XS\
methods of analysis of block jointed rock and their application in excavation engineering $gZC"~BR
and support and reinforcement design. More generally, improved understanding je_:hDr
of the mechanics of discontinuous rock has had a profound effect on simulation of qiEw[3Za]'
caving mechanics and therefore on the design and operation of block caving and = BcKWC
sublevel caving mines. I'6wh+
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Mining-induced seismicity and the related phenomenon of rockbursts have become Z:>)5Z{'
more prevalent in hard rock mining. Developments in mineworthy seismic equipment r<< ]41
and associated data recording, processing and analysis hardware and software have og0su
contributed greatly to measurement, characterisation and management of the problem. t&5N{C:
These developments have been complemented by measures in excavation design \ZNUt$\
and extraction sequencing which have done much to mitigate the serious operating O5X@'.#rU
problems which can occur in seismically active, rockburst prone mines. In large-scale yW3!V-iA
open stope mining, Canadian developments based on pillarless stoping, formulation u!4i+7}
of extraction sequences which promote the evolution and uniform displacement of a RuyqB>[o
regular mine stress abutment, and the extensive use of cement-stabilised backfill, have ViZ Tl~
been successful in managing an acute mining challenge. Notably, these measures have BwpEIV@b]
been based on sound conceptual and analytical models of the relation of damaging xF4S
seismicity to induced stress, geological structure, potential rock displacements and
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strain energy release during mining. kAc8[Hn
Some remarkable developments in computational methods have supported these +H"[WZ5
improvements in rock mechanics practice. Many mining rock mechanics problems >6yA+?[:
are effectively four-dimensional, in that it is the evolution of the state of stress over the #aHPB#
time scale of the mining life of the orebody which needs to be interpreted in terms of D,R"P }G
the probable modes of response of the host rock mass. The computational efficiency EWz,K]_'
of tools for three-dimensional stress analysis now permits modelling of key stages of >3aB{[[N
an extraction sequence, for example, as a matter of routine rock mechanics practice. <}Hfu-PLo
Similarly, computer power and efficient algorithms provide a notable capacity to imb.CYS74
simulate the displacement and flow of rock in cave mining and to support design of 1jHugss9|
optimum caving layouts. okwkMd-yW
Notwithstanding these developments, it is encouraging to note continued attention p>Z18
to formal mathematical analysis in solution of rock mechanics problems. The results i2bkgyzB.
of such analysis provide the canonical solutions for the discipline of rock mechanics ,xcm:;&
and ensure a sound base for both the science and engineering practice. Xy(8}
In preparing this extensive revision, the authors have been fortunate to have the KHnq%#
support of many colleagues and several organisations. In particular, they would like `Hlv*" w$
to record the helpful advice and comment of colleagues on possible improvements
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in earlier editions of the book and in identifying inevitable errors in the text. They ZC7ZlL_
acknowledge the generous assistance of the Brisbane office of Golder Associates in 8v{0=9,Z
providing facilities and many helpful services, particularly in assistance with drafting 6:\0=k5
of the figures for this edition. One of the authors was supported for part of the 'PO+P~|oa&
work of revision by The University of Western Australia, and the other by the Julius PB[Y^q
Kruttschnitt Mineral Research Centre of The University of Queensland. This support, }4$k-,1S
including the associated library services, is acknowledged with gratitude. The authors a -[:RJW
thank the many individuals and organisations who generously gave permission to use K=Q<G:+&V
published material. Finally, they record the encouragement of publisher’s representative, !*I0}I
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Petra van Steenbergen, and her patient assistance and advice during this major Bs?B\k=
undertaking. -/^a2_d[
B. H. G. B. hIBW$
E. T. B. [f ._w~
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