Rock mechanics for underground mining, 3rd ed wa5wkuS)ld
.]JGCTB3
by Rq|7$O5
Et}S*!IS
B. H. G. Brady JUHmIFjZ
Emeritus Professor, The University of Western Australia, and Consulting 6* (6>F5
Engineer, Montville, Queensland, Australia `8/K+ e`
a~>+I~^K5q
E. T. Brown Q9Sh2qF^2
Emeritus Professor, The University of Queensland, and Senior Consultant, @l41'?m
Golder Associates Pty Ltd, Brisbane, Australia *?:V)!.2z
Ixk L]
KLUWER ACADEMIC PUBLISHERS W9+H/T7!
V9mqJRFJ:
2005 Springer Science + Business Media, Inc I r]#u]Ap
\C#XKk$OE
Preface to the third edition ]QlgVw,
Sometimes it is suggested that mining engineering and its supporting engineering j
Jt"=
sciences have reached a state of maturity. However, this proposition is inconsistent eVGO6 2|!
with major developments in the twenty years that have elapsed since the preparation of &s-iie$"@x
the first edition of this book, and the ten years since it has been subject to any substantial jb|al[p\
revision. Over those periods, innovations and improvements in engineering practice !:]CKbG
in mining and mining rock mechanics, and advances in the engineering science of
LhKaqR{
rock mechanics, have been extraordinary. For these reasons the third edition, which \!x~FVA
results from comprehensive and thorough revision of the earlier editions, has involved '1'De^%6W
the replacement or substantial modification of the equivalent of about half of the text *c3(,Bmw
and figures of those versions of the book. C8W#$a
One of the key drivers for many significant developments in fundamental rock mechanics 5_ !s\ 5
over the period has been the mining industry’s recognition of the economic 2<q>]G-nN
returns of better understanding and more rigorous application of the governing sciences
ltK\)L
embedded in its industrial operations and processes. The result has been some aA7}>
notable advances in mining engineering practice, involving improvements in mining >k }ea5+
methods in particular. For example, caving methods are now more widely applied yS'W ss
as understanding of their scientific basis has improved and their economic and operational zmB6Y
t
advantages have been realised. Whereas sublevel caving was once regarded K&3,J7&&
in some places as a method of marginal interest, the advent of very large scale sublevel hSr2<?yk
caving, made possible in part by improved drilling technology and in part by qr~P$
understanding of the governing rock mechanics, it is now an attractive proposition for VKqIFM1b
many orebodies. Similarly, block caving is now conducted efficiently and reliably in Jz<-B
orebody settings that would have been inconceivable two decades ago. At the same #ue WU
time, methods such as overhand cut-and-fill stoping and shrink stoping have declined G)t_;iNL|
in application, replaced in part by open stoping and bench-and-fill stoping, where large `tw[{Wb
scale mechanisation, improved backfill technology, reliable rock mass reinforcement
\,&,Q
of stope walls and the intrinsic advantages of non-entry methods of working have led C-u'Me)H
to superior economics and enhanced operational safety. g(& hu S
The scope of developments in mining rock mechanics science and practice has been {<+B>6^
as impressive as that in mining engineering. Perhaps the most significant advance has '"qTmo!
been the resolution of some longstanding issues of rock fracture, failure and strength n@[_lNa4GD
and their relation to the modes of deformation and degradation of rock around mining (E[c-1s
excavations. The fact that the key research on this topic was conducted at the Underground Se{x-vn?p
Research Laboratory of Atomic Energy of Canada Limited demonstrates the ]Dec/Nnj
extent to which mining rock mechanics has benefited from fundamental research in z@Pv~"
other fields of rock engineering. The mechanics of blocky rock has also been a field of y(^t &tgjS
impressive development, particularly in regard to formulation of a broad spectrum of )31{.c/
methods of analysis of block jointed rock and their application in excavation engineering + Nn
$
and support and reinforcement design. More generally, improved understanding /N '0@q
of the mechanics of discontinuous rock has had a profound effect on simulation of lJb1{\|.,
caving mechanics and therefore on the design and operation of block caving and l1HMH?0|
sublevel caving mines. ;UUpkOQO(
jlXzfDT
Mining-induced seismicity and the related phenomenon of rockbursts have become hg4 d]R,
more prevalent in hard rock mining. Developments in mineworthy seismic equipment v#c'p^T
and associated data recording, processing and analysis hardware and software have tpPP5C{
contributed greatly to measurement, characterisation and management of the problem. 3CcCcZ9I
These developments have been complemented by measures in excavation design RUco3fZ
and extraction sequencing which have done much to mitigate the serious operating h}0}g]IUx
problems which can occur in seismically active, rockburst prone mines. In large-scale
!?)ky `S3
open stope mining, Canadian developments based on pillarless stoping, formulation w`KqB(36
of extraction sequences which promote the evolution and uniform displacement of a VokIc&!Uz
regular mine stress abutment, and the extensive use of cement-stabilised backfill, have Lz6b9W
been successful in managing an acute mining challenge. Notably, these measures have g\%;b3"#
been based on sound conceptual and analytical models of the relation of damaging B>C+qj@
seismicity to induced stress, geological structure, potential rock displacements and PDQEI55
strain energy release during mining. ",O |uL
Some remarkable developments in computational methods have supported these XB0G7o%1
improvements in rock mechanics practice. Many mining rock mechanics problems >8M=REn4
are effectively four-dimensional, in that it is the evolution of the state of stress over the -Y>,\VEK
time scale of the mining life of the orebody which needs to be interpreted in terms of Bie#GKc
the probable modes of response of the host rock mass. The computational efficiency v]{F.N
of tools for three-dimensional stress analysis now permits modelling of key stages of 1K{u>T
an extraction sequence, for example, as a matter of routine rock mechanics practice. vxE#6
Similarly, computer power and efficient algorithms provide a notable capacity to IyK^` y
simulate the displacement and flow of rock in cave mining and to support design of 1*U)\vK~
optimum caving layouts. \no6]xN;
Notwithstanding these developments, it is encouraging to note continued attention E.LD1Pm0
to formal mathematical analysis in solution of rock mechanics problems. The results RGg=dN
of such analysis provide the canonical solutions for the discipline of rock mechanics .Q!_.LX
and ensure a sound base for both the science and engineering practice. x$hhH=
In preparing this extensive revision, the authors have been fortunate to have the EmG':K(
support of many colleagues and several organisations. In particular, they would like ~?#>QN\\c
to record the helpful advice and comment of colleagues on possible improvements AS5'j
in earlier editions of the book and in identifying inevitable errors in the text. They *uW l 804
acknowledge the generous assistance of the Brisbane office of Golder Associates in 2S,N9(7
providing facilities and many helpful services, particularly in assistance with drafting 7qsu0 .[d
of the figures for this edition. One of the authors was supported for part of the O2{~Q{p
work of revision by The University of Western Australia, and the other by the Julius e%[0
NVo
Kruttschnitt Mineral Research Centre of The University of Queensland. This support, ddK\q!0
including the associated library services, is acknowledged with gratitude. The authors )SU\s+"M
thank the many individuals and organisations who generously gave permission to use iq1HA.X(
published material. Finally, they record the encouragement of publisher’s representative, hQ7-m.UZw
Petra van Steenbergen, and her patient assistance and advice during this major zbY2gq@?
undertaking. 4*Uzomb?q
B. H. G. B. 7XzhKA6
E. T. B. *yl?M<28
p+7G