Tunnelling: Management by design Alan Muir Wood London and New York First published 2000 by E & FN Spon 11 New Fetter Lane, London EC4P 4EE Simultaneously published in the USA and Canada by E & FN Spon, an imprint of Routledge 29 West 35th Street, New York, NY 10001 E & FN Spon is an imprint of the Taylor & Francis Group This edition published in the Taylor & Francis e-Library, 2002. © 2000 Alan Muir Wood All rights reserved. No part of this book may be reprinted or reproduced or utilised 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 or retrieval system, without permission in writing from the publishers. The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data Muir Wood, A.M. (Alan Marshall) Tunnelling: management by design/Alan Muir Wood. p. cm. Includes bibliographical references and index. ISBN 0-419-23200-1 (hb: alk. paper) 1. Tunneling. 2. Tunnels—Design. I. Title. TA805.M85 2000 624.1´93–dc21 ISBN 0-203-47766-9 Master e-book ISBN ISBN 0-203-78590-8 (Adobe eReader Format) ISBN 0-419-23200-1 99–047534 Contents Preface vii Notation ix Introduction 1 1 Background to modern tunnelling 8 1.1 Introduction 8 1.2 Tunnelling in antiquity 9 1.3 Development of rationale 12 1.4 New methods, tools and techniques 14 1.5 Towards the present day 19 1.6 The developing problems of management 34 2 Design: the ubiquitous element 37 2.1 The nature of design and its application to tunnelling 37 2.1.1 Characteristics of design 38 2.1.2 The parties to the design process 39 2.1.3 Uncertainty and risk 40 2.1.4 Qualifications for the design team 47 2.2 Steps in the design process 48 2.3 Examples of application of the principles 54 2.4 Construction (Design and Management) Regulations 55 2.5 Pitfalls in the design process 56 2.6 The observational approach 60 2.7 The Observational Method and Observational Design 63 iv Contents 3 Planning 70 3.1 Introduction to planning 70 3.1.1 Assessment between options 72 3.1.2 In the beginning 74 3.1.3 Planning unfolds 77 3.2 Financial planning 81 3.3 The law: facilitator or tripwire? 82 3.4 Competence in planning 85 3.5 Coordinated planning of projects 87 3.5.1 Multiple-purpose projects 87 3.5.2 Serial planning of projects 87 3.6 Issues of procurement of concern to planning 89 3.7 Reliability of forecasting 90 3.7.1 Political influence 90 3.7.2 Authorship of estimates 91 3.7.3 Economic and political factors 92 3.7.4 Timing of completion 92 3.7.5 Development of competitors 92 3.7.6 Ranges and qualifications 92 3.7.7 Attention to ‘climate of risk’ 92 3.7.8 Changes in requirements, including uncertainty and vacillations 93 3.7.9 Contractual relationships 93 3.7.10 Tendering processes 94 3.7.11 Inflexible programming 94 3.8 Practical examples of success and failure in planning 95 4 Studies and investigations 97 4.1 The methodical acquisition of data 97 4.1.1 Studies relating to operation 97 4.1.2 Studies relating to the execution of the project 99 4.1.3 Instrumentation and its interpretation 106 4.2 How not to manage the site investigation 108 4.3 How much site investigation? 111 4.4 Reporting on site investigation 114 4.5 Identification of patterns in the ground 119 4.6 Specific features of site investigation 121 Contents v 5 Design of the tunnel project 131 5.1 Options in tunnel design 131 5.1.1 The nature of the ground 131 5.1.2 Drill-and-blast 146 5.1.3 Tunnels with Informal Support 146 5.1.4 Squeezing ground 149 5.1.5 Tunnels driven by TBM or Shield 149 5.2 Design of the support system 151 5.2.1 Steel arches 151 5.2.2 Informal Support for tunnels in weak and squeezing ground 152 5.2.3 Segmental linings 154 5.2.4 Tunnel junctions and enlargements 160 5.3 Ground movements and surface settlement 162 5.4 Pressure tunnels 166 5.5 Aids to design calculation 167 Appendix 5A The circular tunnel in elastic ground 167 Appendix 5B Cylindrical cavity with internal support 170 Appendix 5C Spherical cavity with internal support 175 Appendix 5D The reinforced rock arch 177 Appendix 5E The brickwork or masonry tunnel 177 Appendix 5F The ground model 180 Appendix 5G Ground-water flow into a tunnel 182 6 Design of construction 186 6.1 The construction process 186 6.1.1 Prediction 188 6.1.2 Execution 189 6.1.3 Observation 193 6.2 The initial phases 198 6.2.1 Bidding strategy 198 6.2.2 The early phase of construction 201 6.3 Choice of method 203 6.4 Special expedients 210 vi Contents 7 Management 215 7.1 Introduction 215 7.2 Project procurement 217 7.3 The ‘zero-sum’ fallacy 219 7.4 The functions of project management 222 7.5 Principles of project management 226 7.6 Project management in practice 227 7.7 The team and the contract 230 8 Hazards, disputes and their resolution 243 8.1 Introduction 243 8.2 Hazards in construction 245 8.3 Methane 252 8.4 Defects during operation 257 8.5 Disputes 260 8.5.1 Causes of disputes 260 8.5.2 Resolution of disputes 263 9 Coda: the Heathrow Tunnel collapse 271 9.1 The context of the project 271 9.2 The project unfolds 275 9.3 Technical explanations of the collapse 280 9.4 Failures of management 280 9.5 Summary of factors contributing to failure 285 9.5.1 The project management 285 9.5.2 Relationships between design and construction 286 9.5.3 Acceptance standards for construction 286 9.5.4 Compensation grouting 287 9.5.5 Monitoring 287 9.5.6 Failure to investigate 288 9.6 Events post collapse 288 References 289 Author Index 300 Subject Index 303 Preface Every author will claim that his or her book will cast light on aspects of the chosen topic not previously illuminated by his (or her—to be understood throughout) precursors. Where then are the dark unexplored recesses of the underground world that justify the promised light at the end of the tunnel of this present account? The immediate spur to writing this book is that the author has lived and worked through a period of revolutionary change in tunnelling, with several components: • change from traditional craft to technological art; • spectacular advances in site investigation techniques and in geotechnical analysis; • great strides in technological development in all aspects of tunnel construction; • emphasis on the teachable elements of science applied to tunnelling; • recognition of the interplay of opposites: opportunity and risk, in the development of tunnelling strategies; • institutional recognition of tunnelling as a specific branch of engineering. But costly mistakes—possibly costing more than the original estimate of the project—are now more common occurrences, usually of a foreseeable and preventable nature. Overall, therefore, the industry is nowhere near optimum potential, to the frustration of those who work in it, the wasting of personal effort, the thwarting of the objectives of the promoters of projects who, in the most egregious failures, have themselves through lack of understanding established conditions unconducive to success. Where lawyers earn far more from the failure of projects than do the most skilled engineers from success, clearly there are fundamental systemic faults. From the surface, no single explanation for this contradictory situation is apparent but deeper digging indicates a common set of system failures. A primary purpose of this book is therefore to see tunnelling as a system and to viii Preface develop principles for success based on effective understanding and operation of the system of interplay of specific tunnelling skills. The views expressed in this book are the author’s own but he acknowledges his debt to his many immediate colleagues in Halcrow and to so many tunnellers and others around the world for several of the thoughts which have prompted the book. The author accepts full responsibility for any misunderstanding. The account may be criticised as unduly orientated towards the British and European examples. This is justified by selecting examples for which the circumstances are generally familiar; lessons learned may well have more universal application. The Channel Tunnel, for example, provides many examples of meritorious engineering with less meritorious management. An exemplary account of its engineering geology (Harris et al. 1996) attracts numerous references on account of its depth and breadth. Notation Against each symbol is a brief definition and a reference to the most appropriate Section or Appendix of the book for further explanation. a major semi-diameter of ellipse 9.3 a tunnel radius App. 5A A cross-sectional area of tunnel 5.3 b minor semi-diameter of ellipse 9.3 c cohesion 5.1.1 ca concentration of gas in air 8.3 cu undrained shear strength of soil 5.1.1 cv coefficient of consolidation 5.1.1 cw concentration of gas dissolved in water 8.3 C construction hazard 6.1.3 C circumference 9.3 Cp velocity of compressive wave 4.1.2 Cs velocity of shear wave 4.1.2 d10 size of tenth smallest fraction 6.3 D design of project hazard 6.1.3 E Young’s modulus for lining App.