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• • SOILM AND F5(j}!ANICS DATIONS A C A R E S O U F SOIL MECHANICS AND FOUNDATIONS MUNI BUDHU JOHN WilEY & SONS, INC. "lew York / Chichestcr IlVeillheim I Brisballe I 5111gopore I TorOIlfO Editor Wayne Anderson Marketing Manager Katherine Hepburn Semor Production Manager Lucille Buonocore Production Editor Leslie Surovick Cover Designer Lynn Rogan Illustration Editor Sigmund Malinowski Illustration Studio Radianl Illustration II:- Design Cover Photo CORBISlRogu Wood This book was set in 10112 Times Ten by UG I GGS Informati pnnted and bound by RR DonnelJey/Wiliard. The cover was p Corporation. e This book is printed on acid-free paper. The paper in this book was manufactured by a include sustained yield harvesting of tts timbedan tf'J''t';'<illllo" principles ensure that the numbers of of new growth. in a remeval system or Ira.nsmillcd • scanning United States permission o( tile Publisher. or , per-copy fee to the Copyright MA 01923. (SOB) 750-8400. fu for permission should be addressed 10 the &. Sam. Inc_. 605 Third Avenue, New York. NY fax (2!2) 850-6008, e-mail: PERMREQ®WILEY.COM. Il·8O(j-CALL·WILEV (225·5945). LiI',• ., .,t,~"g)"'C","I,>g".g ill Publicalio" Dala: s.;:1 n"'~!>!;:'" 'nd foundations I by Munt Budhu. p. ISBN 0-47!·25131·X (aU::. paper) 1. Soil mechanu;s. 2. Foundations. I. Tilte. TA710.B765 1999 624.1'513622] 99-050184 Printed in the United States of Amenca 10 9 8 1 6 5 4 3 2 PREFACE F • Professor Hilary 1. Inyang, University of Massachusetts-Lowell • Professor Derek Morris, Texas A&M University • Professor Cyrus Aryani, California State University 111181 v vi PREFACE • Professor Shobha K. Bhatia, Syracuse University • Major Richard L. Shelton, United States Military Academy • Professor Colby C. Swan, University of Iowa • Professor Panos I(jousis, University of Arizona • Professor Carlos Santamarina, Georgia Institute of Tech • Dr. William Isenhower, Ensoft, Inc. Mr. Wayne Anderson and his staff, and Leslie S Sons were particularly helpful in getting this book done. to my wife and children who have contributed 1!mifican this book. O F NOTES for Instructors I would like to present some guidance to assist you i graduate geotechnical engineering courses. DESCRIPTION OF CHAPTERS O F tlement is interpreted and the parameter required to determine time rate of settlement. The oedometer test is described and procedures to determine the various parameters for settlement calculations are presented. Chapter 5 deals with the shear strength of soils and the tests (laboratory and field) required for its determination. The Mohr-Coulomb failure criterion is discussed using the student's background in strength of materials (Mohr's circle) and in statics (dry friction). Soils are treated as a dilatant-frictional material vii viii NOTES FOR INSTRUCTORS rather than the conventional cohesive-frictional materifll. Typical stress-strain responses of sand and clay are presented and discussed. The implications of drained and undrained conditions on the shear strength of soils are discussed. Laboratory and field tests to determine the shear strength of soils are described. Chapter 6 deviates from traditional undergraduate textboqk-topics by deal ing with soil consolidation and strength as separate issues. I~'i.his chap\er, de formation and strength are integrated within the framework 0 britical stilte soil mechanics using a simplified version of the modified c m ay d!!!#fhe em phasis is on understanding the mechanical behavior 0 ~ls ra her than present· ing the mathematical formulation of critical state soil mec a~cs M the modified cam-clay model. The amount of mathematics is ke~o the ~!pjmum needed for understanding and clarification of important co ceptS!--Projection geometry is used to illustrate the different responses 0 soils wh the "'loading changes under drained and undrained loading. Althoug: thisap e eals with a simplification and an idealization of real soils, the real neftt i a simple framework, which allows the stlldent to think abou possJbte i sponses if can itions change from those originally conceive sis usuaun e gineering ~tice It also allows them to better interpret soil test re ults. ,I Chapter 7 deals wi bearing cae.aci1Y and seJ.t'ement of footings. Here bearing capacity and seuleme.pl are tteated as a in~e t~O iC. n the design of foundations. the geotechnical ngineer must be sa 'sfied at th earing capacity is sufficient and ~ttlem nl at working load is lera . Indeed. for most shallow footings. it is settlflT].ent that gover -Iii 1 n. ot bearing capacity. Limit equilibrium analysis is introduced to illu trate the method that has been used to fin the pop~tiearing cap}' Ity equ~ion.s..and LO make use of the SIll dent's ba'tgr nd in statics (equili rium) to mtroduce a simple but powerful analytical t~o . Three sets of bearin capacity equations (Terzaghi as modified by Vesic, M~yerhof. and Sk pton), lh inftuence of groundwater level, and ntric load'to n bearing apacity are discussed. These equations are simplified ~ twi> b breaking them down 1m categories-one relating to drained conditions. a the or er to undraipe~ condi ·ons~laS{ic. one-dimensional consolidation. and Sk: ~pton and BjerQ!...nLs m thod'of determining settlement are presented. The elastic methodA~ findingSe-tt ement is based on work done by Gazettas (1985), who descri1)ed p blems a ociated with the Janbu, Bjerrum, and Kjaernali (1956) m 1\od that conventionally quoted in textbooks. ~ Pile fo dalio are described and discussed in Chapter 8. Methods for finding bearing ~pacity and settlement of single and group piles are presented. Chapter 9 is about [wo-dimensional steady state flow through soils. Solu tions to two-dimensional flow using flow nets and the finite difference technique' are discussed. Emphases are placed on seepage. pore water pressure, and insta- bility. This chapter normally comes early in most current textbooks. The reason for placing this chapter here is because two-dimensional flow influences the sta bility of earth structures (retaining walls and slopes), discussion of which follows in Chapters 10 and 11. A student would then be able to make the practical connection of two-dimensional flow and stability of geotechnical systems readily. Lateral earth pressures and their use in the analysis of earth retaining sys tems and excavations are presented in Chapter 10. Gravit)' and flexible relaining walls. in addition \0 reinforced soil walls, arc discussed. Guidance is provided as to what strength parameters to use in drained and undrained conditions. NOTES FOR INSTRUCTORS ix Chapter 11 is about slope stability. Here stability conditions are described based on drained or undrained conditions. An appendix (Appendix A) allows easy access to frequently used typical soil parameters and correlations. CHAPTER LAYOUT F dvent 0 ersonal computers, learning has become more visual. Some, studies hav epo[ ed that visual images have improved learning by as much as 400%. This tex-t ok is accompanied by a CD ROM that contains text, interactive animation, images, a glossary, notation, quizzes, notepads, and interactive prob lem solving. It should appeal, particularly, to visual learners. A quiz is included in appropriate chapters on the CD ROM to elicit per formance and provide feedback on key concepts. Interactive problem solving is used to help students solve problems similar to the problem-solving exercises. When an interactive problem is repeated, new values are automatically gener ated. Sounds are used to a limited extent. The CD ROM contains a virtual soils laboratory for the students to conduct geotechnical tests. These virtual tests are not intended to replace the necessary hands-on experience in a soil laboratory. Rather, they complement the hands-on experience, prepare the students for the real experience, test relevant prior knowledge of basic concepts for the interpre-