PRINCIPLES OF ENGINEERING GEOLOGY PRINCIPLES OF ENGINEERING GEOLOGY P. B. ATTEWELL and I. W. FARMER University of Durham LONDON CHAPMAN AND HALL A Halsted Press Book JOHN WILEY & SONS, INC., NEW YORK First published 1976 by Chapman and Hall Ltd 11 New Fetter Lane, London EC4P 4EE © 1976 J. E. Attewell and L. C. Attewell Sriftcover reprillt rifthe hardcover 1ft editiolt 1976 Typeset by Preface Ltd, Salisbury, Wilts Fletcher & Son Ltd, Norwich ISBN-13: 978-94-009-5709-1 e-ISBN-13: 978-94-009-5707-7 DOl: 10.1007/978-94-009-5707-7 All rights reserved. No part of this book may be reprinted, or reproduced or utilized in any form or by any electronic, mechanical or other means, now known or hereafter invented, including photocopying and recording, or in any information storage and retrieval system, without permission in writing from the Publisher. Distributed in the U.S.A. by Halsted Press, a Division of John Wiley & Sons, Inc., New York Library of Congress Cataloging in Publication Data Attewell, P B Principles of engineering geology. 1. Engineering geology. I. Farmer, Ian William, joint author. II. Title. TA705.A87 1975 624'151 75-20012 Contents Preface xi Symbols xvii Composition of Rocks 1 1.1 Origin and geological classification of rocks 1 1.2 Rock forming minerals 7 1.3 Clay minerals 16 1.4 Base exchange and water adsorption in clay minerals 20 1.5 Mineralogical identification 25 2 Rock Particles and Particle Systems 30 2.1 Rock particle classification 30 2.2 Typical rock particle systems 33 2.3 Physical properties of particulate systems 42 2.4 Permeability of particulate systems 45 2.5 Representation of stress in a soil mass 48 2.6 Effective stress 56 2.7 Frictional properties of rock particles 60 2.8 Soil deformation - drained granular media 66 2.9 Soil strength - drained granular media 75 2.10 Soil strength and deformation - clay soils 81 2.11 Pore pressure parameters 88 2.12 Rate of porewater pressure dissipation 92 2.13 The critical state concept 97 2.14 Limiting states of equilibrium 100 3 Clays and Clay Shales 104 3.1 Interparticle attraction and repulsion 105 3.2 Sediment formation and clay fabrics 109 3.3 Unstable clay fabrics 117 3.4 Glacial and periglacial clays 122 vi Contents 3.5 Depth - strength profiles 125 3.6 Macrostructure of overconsolidated clays and clay shales 130 3.7 Engineering influence of discontinuities in clay shales 143 3.8 Classification of clay shales 146 3.9 Consolidation and diagenetic considerations 150 3.10 Physical breakdown of shales 153 3.11 Suction pressure 157 3.12 Swelling pressure 162 3.13 Chemical and mineralogical analyses of clays 167 3.14 Relationship between mineralogy, geochemistry and geo- technical properties of clays and clay shales 175 4 Rock as a Material 182 4.1 Uniaxial strength 184 4.2 Uniaxial short-term deformation 194 4.3 Deformation mechanisms in rock 199 4.4 Complete stress - strain characteristics of rock in uniaxial compression 206 4.5 Effect of rate and duration of loading 210 4.6 Deformation and failure of rocks in triaxial compression 218 4.7 Failure criteria for rocks 224 4.8 Yield criteria 229 4.9 Rock dynamics 232 4.10 Wave transmission through rocks 234 4.11 Wave attenuation 239 4.12 Rock as a construction material 244 5 Preferred Orientation, Symmetry Concepts and Strength Anisotropy of some Rocks and Clays 250 5.1 Studies of the orientation density distribution of clay minerals and other associated minerals 251 5.2 X-ray texture goniometry 252 5.3 Symmetry concepts 260 5.4 Deformation paths 263 5.5 Deformation ellipsoid 263 5.6 Randomization 266 5.7 Symmetry elements and sub-fabrics 271 5.8 Crystallographic plane multiplicities and symmetry 272 Contents vii 5.9 Engineering influence of intrinsic anisotropy 285 5.10 Comparative degree of intrinsic anisotropy - mechanical evidence from rock experimentation 288 5.11 Intrinsic strength anisotropy of brittle and semi-brittle rocks comprising a dominant clay mineral control 289 5.12 Intrinsic anisotropy and sedimentation 300 5.13 Anisotropy of clay shales 302 5.14 Clay strength anisotropy 302 6 Rock Discontinuity Analysis 315 6.1 The engineering interest in discontinuities 315 6.2 Genesis and modification of fissures and slickensides 317 6.3 Controls on fissuring and fissure patterns 319 6.4 Classification of discontinuities 320 6.5 Character of discontinuities 326 6.6 Test specimen size-strength relationships 326 6.7 Stereographic representation of discontinuity data 328 6.8 Direct and inverse transformations from polar to equatorial angles 329 6.9 Linear orthogonal transformations 333 6.10 Eulerian angles 336 6.11 Discontinuity survey techniques 336 6.12 Analysis of discontinuity data 344 6.13 Influence of gouge material and surface roughness characteristics of discontinuities 352 6.14 Distributions 355 6.15 Orientation density distribution of discontinuities 364 6.16 Discontinuity shear stability in a poly axial stress field 369 6.17 Shear strain energy concepts 376 6.18 Preliminary consideration of certain types of discontinuity structure in two dimensions 385 6.19 Statistics of scanlines through discontinuity distributions 388 6.20 Continuity 394 6.21 Preliminary shear stability analysis of discontinuities at the foundation interface of an earth or rock-fill dam 398 6.22 Stability of jointed rock in the foundation of an arch dam 409 6.23 Stability of a discontinuous clay surrounding an unlined tunnel 426 viii Contents 7 Site Investigation 427 7.1 Preliminary investigation 429 7.2 Aerial photographs 437 7.3 Terrain evaluation for highway projects 442 7.4 Geophysical exploration techniques 448 7.5 Seismic refraction surveying 453 7.6 Site exploration 457 7.7 Borehole logging 465 7.8 Sampling and testing 475 7.9 Site investigation reports 483 7.10 Mechanical tests in situ 484 7.11 Field monitoring techniques 503 7.12 Use of field seismic techniques in engineering geology 512 7.13 Analysis of ground vibrations 514 7.14 Marine geotechnical exploration 529 7.15 Mining subsidence 534 7.16 Probability theory in site investigation 547 7.17 What is 'safety' in soil and rock mechanics? 557 8 Groundwater 560 8.1 Types of subsurface water 560 8.2 Groundwater flow 565 8.3 Seepage forces 577 8.4 Drainage and drain wells 580 8.5 Permeability tests - rock 585 8.6 Permeability tests - soils 591 8.7 Economic exploitation of groundwater 598 8.8 Ownership of groundwater and permitted abstractions 601 8.9 Groundwater exploration 601 8.10 Regional investigations 614 8.11 Simulation of groundwater regimes 618 8.12 Well losses 626 8.13 Improving aquifer yield 627 8.14 Groundwater quality 627 9 Stability of Soil Slopes 632 9.1 Planar slides 633 9.2 Circular failure surfaces 635 9.3 Slope stability case histories 645 Contents ix 9.4 Simple wedge method of analysis 661 9.5 Use of design curves 672 9.6 Pore pressure ratio 674 9.7 Oay slopes and shear strength parameters 675 9.8 Slope angle measurements in clays and clay shales 683 9.9 Classification of gravitational mass movements in clay 688 9.10 Rock breakdown and landform development 697 9.11 Geomorphological classification of slope profile development 704 9.12 General methods of preventing slope failure 705 9.13 Highway slopes 708 9.14 Protection against coastal erosion 714 10 Rock Slope Stability 720 10.1 Geomorphological classification of rock slope instabilities 720 10.2 Classification of rock masses 730 10.3 Character of joints in rock masses 738 10.4 Engineering recognition of rock failure modes 743 10.5 Surface roughness of joints 749 10.6 Discontinuity roughness classification 753 10.7 Planar sliding and the friction cone concept 758 10.8 Instability on intersecting joint planes 765 10.9 Influence of discontinuity orientation distributions 787 10.10 Seismic influences on stability with respect to sliding 792 10.11 Instability caused by block overturning 797 10.12 General rock slope design curves 803 10.13 Slopes in highway cuttings and embankments 809 II Ground Improvement 814 11.1 Shallow compaction 817 11.2 Deep compaction 821 11.3 Pre-loading and consolidation 826 11.4 Sand drains 830 ll.5 Grout treatment 836 11.6 Fissure grouting 851 11.7 Hydrofracture 855 ll.8 Cavity grouting 863 11.9 Electro-chemical stabilisation 866 11.10 Groundwater freezing 871 x Contents 11.11 Bentonite suspension 874 1l.12 Ground anchors 879 12 Water Resources, Reservoirs and Dams 887 12.1 Water requirements in England and Wales 888 12.2 Planning of water resources 889 12.3 Conjunctive use schemes 895 12.4 Flood and dam design parameters 897 12.5 Channel protection 900 12.6 Design capacity of a storage reservoir 904 12.7 Air-photo interpretation for catchment development 907 12.8 Geological influences upon the selection of reservoir sites 908 12.9 Foundation investigations 911 12.10 Water movement into and out of a reservoir 914 12.11 Synthetic flow generation techniques 917 12.12 Dam foundations 918 12.13 Classification of dam types according to their purpose, construction and foundation geology 922 12.14 Long term stability of earth dams 944 12.15 Dam seismicity 945 References 969 Supplementary References 1022 Author Index 1025 Subject Index 1035 Preface 'Engineering geology' is one of those terms that invite definition. The American Geological Institute, for example, has expanded the term to mean 'the application of the geological sciences to engineering practice for the purpose of assuring that the geological factors affecting the location, design, construction, operation and mainten­ ance of engineering works are recognized and adequately provided for'.