ROCK MECHANICS

Rock Mechanics

Frontispiece Post-pillar mining in a
jointed and faulted rock mass at the
Dolphin Mine, King Island, Australia
(photograph by permission of King Is-
land Scheelite and CSIRO Division of
Geomechanics).

Rock
Mechanics
for underground mining
Third edition
B. H. G. Brady
Emeritus Professor, The University of Western Australia, and Consulting
Engineer, Montville, Queensland, Australia
E. T. Brown
Emeritus Professor, The University of Queensland, and Senior Consultant,
Golder Associates Pty Ltd, Brisbane, Australia

A catalogue record for this book is available from the British Library
Printed on acid-free paper
All Rights Reserved
First edition 1985
Second edition 1993
Third edition 2004
C
No part of this work may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, microfilming,
recording or otherwise, without written permission from the Publisher, with the
exception of any material supplied specifically for the purpose of being
entered and executed on a computer system, for
exclusive use by the purchaser of the work.
Published by Springer,
www.springer.com
1985, 1993, 2004, 2006 B.H.G. Brady and E.T. Brown
Reprinted with corrections 2006
A CIP Catalogue record for this book is available from the Library of Congress
ISBN-10 1-4020-2064-3 (PB)
P.O. Box 17, 3300 AA Dordrecht, The Netherlands.
ISBN-10 1-4020-2116-X (e-book)
ISBN-13 978-1-4020-2116-9 (e-book)
ISBN-13 978-1-4020-2064-3 (PB)

Contents
Preface to the third edition xi
Preface to the second edition xiii
Preface to the first edition xv
Acknowledgements xvii
1 Rock mechanics and mining engineering 1
1.1 General concepts 1
1.2 Inherent complexities in rock mechanics 4
1.3 Underground mining 6
1.4 Functional interactions in mine engineering 9
1.5 Implementation of a rock mechanics programme 13
2 Stress and infinitesimal strain 17
2.1 Problem definition 17
2.2 Force and stress 17
2.3 Stress transformation 19
2.4 Principal stresses and stress invariants 23
2.5 Differential equations of static equilibrium 25
2.6 Plane problems and biaxial stress 26
2.7 Displacement and strain 29
2.8 Principal strains 33
2.9 Strain compatibility equations 34
2.10 Stress-strain relations 34
2.11 Cylindrical polar co-ordinates 37
2.12 Geomechanics convention 39
2.13 Graphical representation of biaxial stress 41
Problems 43
3 Rock mass structure and characterisation 46
3.1 Introduction 46
3.2 Major types of structural features 47
3.3 Important geomechanical properties of discontinuities 51
3.4 Collecting structural data 57
3.5 Presentation of structural data 69
3.6 The hemispherical projection 71
3.7 Rock mass classification 77
Problems 82
4 Rock strength and deformability 85
4.1 Introduction 85
4.2 Concepts and definitions 86
v