Developments in Geotechnical Engineering. Series editors Braja M. Das, Henderson, USA Nagaratnam Sivakugan, Townsville, Australia

Transcription

1 Developments in Geotechnical Engineering Series editors Braja M. Das, Henderson, USA Nagaratnam Sivakugan, Townsville, Australia

2 More information about this series at

3 Sanjay Kumar Shukla Fundamentals of Fibre-Reinforced Soil Engineering

4 Sanjay Kumar Shukla Discipline of Civil and Environmental Engineering School of Engineering, Edith Cowan University Perth, WA, Australia ISSN ISSN (electronic) Developments in Geotechnical Engineering ISBN ISBN (ebook) DOI / Library of Congress Control Number: Springer Nature Singapore Pte Ltd This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. Printed on acid-free paper This Springer imprint is published by Springer Nature The registered company is Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #22-06/08 Gateway East, Singapore , Singapore

5 Preface In the current construction practice, reinforcing the soil is an effective and reliable ground improvement technique for increasing the strength and stability of the soil in various applications, including retaining structures, embankments, foundations, slopes and pavements. The concept of reinforcing the soil with natural materials was originated in ancient times; however, the galvanized steel strips, having a high tensile modulus, are the earliest modern form of soil reinforcement developed in 1966 in France. Later, the use of polymeric products, called the geosynthetics, started as the soil reinforcement along with several other applications of specific geosynthetics to achieve different functions as separation, filtration, drainage, fluid barrier and protection. In the noncritical structures, natural products, called the geonaturals, are also used as the soil reinforcement. Unlike the metal strips, in general, the geosynthetic and geonatural reinforcements have a much lower tensile modulus. Geosynthetic reinforcements (woven geotextiles, geogrids, some geocomposites, etc.) as well as geonatural reinforcements (bamboo, geocoir, geojute, etc.) are generally used in the form of flexible sheets/mats/meshes. The subject of geosynthetics and geonaturals and their applications are called the geosynthetic engineering, and there are some textbooks and reference books available on this subject. Reinforcing the soil with flexible, discrete fibres is not a new technique in civil/geotechnical engineering. However, as the fibre inclusions bring several technical, economic and environmental benefits, in recent years, a great deal of interest has been created worldwide on the potential applications of fibres within the soils and other similar materials, such as coal ashes and mine tailings. Fibres are generally available in large amounts in natural and waste forms. In many countries, waste fibres (plastic waste fibres, old tyre fibres, etc.) have been creating disposal and environmental problems. Utilization of these fibres in constructions can solve the disposal problems in a cost-effective and environmentally friendly manner. Over the past years, the laboratory and field research studies have shown that the use of natural, synthetic and waste fibres as a tension-resisting element and/or an admixture causes significant modification and improvement in the v

6 vi Preface engineering properties (strength, stiffness, permeability, compressibility, etc.) of soils and other similar materials. The soil reinforced randomly with short, discrete fibres is basically a composite material and is called the randomly distributed fibrereinforced soil, or simply the fibre-reinforced soil. The studies indicate that a fibrereinforced soil exhibits greater extensibility and a smaller loss of post-peak strength; that is, compared to soil alone, the fibre-reinforced soil is more ductile. Soils, especially cohesionless soils, can also be reinforced by the continuous fibres/ yarns. In this reinforcing system, a single monofilament is spun or injected in a random pattern simultaneously with the deposition of soil in a specific application. This book presents the fundamentals of the fibre-reinforced soils within five chapters as an engineering subject, called the fibre-reinforced soil engineering. No complete book is currently available on this subject. The book is primarily designed and developed as a textbook as well as a student-centred learning resource for a one-semester course for senior undergraduate and postgraduate students as a part of a geotechnical/civil engineering programme. This course may be offered to students as an elective in the universities/institutes/colleges. The material in all the chapters of this book is presented clearly in simple and plain English and includes the optimum amount of text, illustrations, tables, examples and questions for practice. Each chapter includes many useful references, quoted in text and listed at the end of the chapter, for further study. As the practical solution to an engineering problem often requires the application of engineering judgement and experience, which can be acquired by regular professional practice and self-study, an attempt has been made to provide the practical experience, including the field application guidelines and some case studies. The chapter summary presented at the end of each chapter may help the readers in getting some key learning points easily. Through this textbook, the readers can learn the subject without any major assistance, and some readers can learn the subject even by self-reading only. Apart from students, researchers and teachers, this textbook will be a valuable learning resource for the practising engineers dealing with utilization of fibres in constructions and infrastructure developments worldwide. For a better learning of the concept of fibre-reinforced soils, it is important to have an understanding of the basic soil properties and core principles of soil mechanics, as presented in Chap. 1, along with the basic description of soil reinforcement. Chapter 2 provides the basic details of fibre-reinforced soils, focusing on fibres and their types, and phase concept along with a brief introduction to the soil reinforced with continuous fibres and multioriented inclusions. Chapter 3 deals with the engineering behaviour of fibre-reinforced soils as reported by various researchers based on their experimental investigations and analyses of test results. Chapter 4 focuses on presenting the reinforcing mechanisms, the models of fibrereinforced soils and findings of some numerical studies. Chapter 5 covers the details of field applications of fibre-reinforced soils, emphasizing on analysis and design concepts, and field application experience and guidelines. The key research developments have been included as required throughout the book. I would like to thank Swati Meherishi, senior publishing editor, Aparajita Singh, RaagaiPriya ChandraSekaran, Rajeswari Sathiamoorthy and other staff at Springer

7 Preface vii for their full support and cooperation at various stages of the preparation and production of this textbook. I wish to extend sincere appreciation to my wife, Sharmila, for her encouragement and support throughout the preparation of the manuscript. I would also like to thank my daughter, Sakshi, and my son, Sarthak, for their patience during my work on this textbook at home. Finally, I welcome suggestions from the readers and the users of this textbook for improving its content in future editions. Perth, 2017 Sanjay Kumar Shukla

8 Contents 1 Basic Description of Soil and Soil Reinforcement Introduction Soil and Its Phases Soil Properties and Core Principles of Soil Mechanics Soil Reinforcement Fibre-Reinforced Soil Engineering References Basic Description of Fibre-Reinforced Soil Introduction Fibres Phases in a Fibre-Reinforced Soil Mass Soil Reinforced with Continuous Fibres and Multioriented Inclusions References Engineering Behaviour of Fibre-Reinforced Soil Introduction Factors Affecting the Engineering Behaviour Shear Strength Observations in Direct Shear Tests Observations in Triaxial Tests Unconfined Compressive Strength Compaction Behaviour Permeability and Compressibility California Bearing Ratio Load-Carrying Capacity Other Properties References ix

9 x Contents 4 Soil Reinforcing Mechanisms and Models Introduction Basic Soil Reinforcing Mechanisms Basic Models of Fibre-Reinforced Soils Waldron Model Gray and Ohashi (GO) Model Maher and Gray (MG) Model Ranjan, Vasan and Charan (RVC) Model Zornberg Model Shukla, Sivakugan and Singh (SSS) Model Other Models and Numerical Studies References Applications of Fibre-Reinforced Soil Introduction Field Applications Analysis and Design Concepts Field Application Experience and Guidelines Scope of Research References Index

10 About the Author Dr Sanjay Kumar Shukla is the founding editor-inchief of International Journal of Geosynthetics and Ground Engineering (Springer International Publishing). He is an associate professor and programme leader of civil and environmental engineering at the School of Engineering, Edith Cowan University, Perth, Australia. He is also an adjunct professor at the School of Civil and Chemical Engineering, VIT University, Vellore, India, and a Distinguished Professor of Civil Engineering at the Institute of Engineering and Technology, Chitkara University, Himachal Pradesh, India. He graduated in 1988 with a first-class degree with distinction in civil engineering from BIT Sindri (Ranchi University, Ranchi), India, and earned his MTech in civil engineering (engineering geology) in 1992 and PhD in civil engineering (geotechnical engineering) in 1995 from the Indian Institute of Technology Kanpur, India. He has over 20 years of teaching, research and consultancy experience in the field of Civil (Geotechnical) Engineering. He is the author of ICE textbooks titled Core Principles of Soil Mechanics and Core Concepts of Geotechnical Engineering, and has authored/co-authored/edited other 7 books and 12 book chapters. He is also the author/co-author of more than 160 research papers and technical articles, including over 100 refereed journal publications. He is a fellow of Engineers Australia, Institution of Engineers (India) and Indian Geotechnical Society and a member of the American Society of Civil Engineers (ASCE), International Geosynthetics Society and Indian Roads Congress. He serves on the editorial boards of the International Journal of Geotechnical Engineering, Ground Improvement, Geotechnical Research, Indian Geotechnical Journal, Cogent Engineering and Advances in Civil Engineering, and he is the scientific editor of the Journal of Mountain Science. xi