Further titles in this series: 1. G. SANGLERAT - THE PENETROMETER AND SOIL EXPLORATION 2. Q. ZARUBA AND V. MENCL - LANDSLIDES AND THEIR CONTROL 3. E.E. WAHLSTROM - TUNNELING IN ROCK 4. R. SILVESTER - COASTAL ENGINEERING, 1 and 2 5. R.N. YONG AND B.P. WARKENTIN - SOIL PROPERTIES AND BEHAVIOUR 6. E.E. WAHLSTROM - DAMS, DAM FOUNDATIONS, AND RESERVOIR SITES 7. W.F. CHEN - LIMIT ANALYSIS AND SOIL PLASTICITY 8. L.N. PERSEN - ROCK DYNAMICS AND GEOPHYSICAL EXPLORATION Introduction to Stress Waves in Rocks 9. M.D. GIDIGASU - LATERITE SOIL ENGINEERING 10. Q. ZARUBA AND V. MENCL - ENGINEERING GEOLOGY 11. H.K. GUPTA AND B.K. RASTOGI - DAMS AND EARTHQUAKES 12. F.H. CHEN - FOUNDATIONS ON EXPANSIVE SOILS 13. L. HOBST AND J. ZAJIC - ANCHORING IN ROCK 14. B. VOIGHT (Editor) - ROCKSLIDES AND AVALANCHES, 1 and 2 15. C. LOMNITZ AND E. ROSENBLUETH (Editors) - SEISMIC RISK AND ENGINEERING DECISIONS 16. C.A. BAAR - APPLIED SALT-ROCK MECHANICS, 1 The In-Situ Behavior of Salt Rocks 17. A.P.S. SELVADURAI - ELASTIC ANALYSIS OF SOIL-FOUNDATION INTERACTION 18. J. FEDA - STRESS IN SUBSOIL AND METHODS OF FINAL SETTLEMENT CALCULATION 19. A. KEZDI - STABILIZED EARTH ROADS 20. E.W. BRAND AND R.P. BRENNER (Editors) - SOFT-CLAY ENGINEERING 21. A. MYSLIVEC AND Z. KYSELA - THE BEARING CAPACITY OF BUILDING FOUNDATIONS 22. R.N. CHOWDHURY - SLOPE ANALYSIS 23. P. BRUUN - STABILITY OF TIDAL INLETS Theory and Engineering 24. Ζ. BAZANT - METHODS OF FOUNDATION ENGINEERING 25. A. KEZDI - SOIL PHYSICS Selected Topics 26. H.L. JESSBERGER (Editor) -GROUND FREEZING 27. D. STEPHENSON - ROCKFILL IN HYDRAULIC ENGINEERING 28. P.E. FRIVIK, N. JANBU, R. SAETERSDAL AND L.I. FINBORUD (Editors) - GROUND FREEZING 1980 29. P. PETER - CANAL AND RIVER LEVEES 30. J. FEDA - MECHANICS OF PARTICULATE MATERIALS The Principles 31. Q. ZARUBA AND V. MENCL - LANDSLIDES AND THEIR CONTROL Second completely revised edition 32. I.W. FARMER (Editor) - STRATA MECHANICS 33. L. HOBST AND J. ZAJIC - ANCHORING IN ROCK AND SOIL Second completely revised edition 35. L. RETHATI - GROUNDWATER IN CIVIL ENGINEERING DEVELOPMENT S IN GEOTECHNICA L ENGINEERIN G 34A PRACTICAL PROBLEMS IN SOIL MECHANICS AND FOUNDATION ENGINEERING, 1 PHYSICAL CHARACTERISTIC S OF SOILS, PLASTICITY, SETTLEMEN T CALCULATIONS , INTERPRETATIO N OF IN-S/TU TESTS GUY SANG LE RAT GILBERT OLIVARI BERNARD CAM BO U Translated by G. GENDARME ELSEVIER Amsterdam — Oxford — New York — Tokyo 1984 ELSEVIER SCIENCE PUBLISHERS B.V. Molenwerf 1 P.O. Box 211, 1000 AE Amsterdam, The Netherlands Distributors for the United States and Canada: ELSEVIER SCIENCE PUBLISHING COMPANY INC. 52, Vanderbilt Avenue New York, N.Y. 10017 Library of Congress Cataloging in Publication Data Sanglerat, Guy, 1921*- Practical problems in soil mechanics and foundation engineering. (Developments in geotechnical engineering ; ) Translation of: Problemes practiques de mecanique des sols et de fondations. Bibliography: v. 1, p. Includes index. Contents: 1 . Physical characteristics of soils, plasticity, settlement calculations, interpretation of in-situ tests. 1. Soil mechanics. 2 . Foundations. I. Olivari, Gilbert. II. Cambou, Bernard. III. Title. IV. Series: Developments in geotechnical engineering ; 3k. TA710.S21+613 198*1 62À*.1'513â 84-10250 ISBN 0-444-42109-2 (U.S. : set) ISBN 0-444-42108-4 (U.S. : v. l) ISBN 0-444-42108-4 (Vol. 34A) ISBN 0-444-41662-5 (Series) ISBN 0-444-42109-2 (Set) © Elsevier Science Publishers B.V., 1984 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photo- copying, recording or otherwise, without the prior written permission of the publisher, Elsevier Science Publishers B.V./Science & Technology Division, P.O. Box 330, 1000 AH Amsterdam, The Netherlands. Special regulations for readers in the USA — This publication has been registered with the Copyright Clearance Center Inc. (CCC), Salem, Massachusetts. Information can be ob- tained from the CCC about conditions under which photocopies of parts of this publica- tion may be made in the USA. All other copyright questions, including photocopying outside of the USA, should be referred to the publishers. í PREFACE by PROF. Dr. VICTOR F.B. De MELLO President International Society for Soil Mechanics and Foundation Engineering 1981—1985 In the continuum of persistent change which characterizes the professional quest for scientific and engineering solutions, there is an absolute need for pauses and movement by steps. Such a need is felt all the more intensely as all social and technological factors have made the continuum of change more and more accelerated. Man, and especially the Engineer, cannot shy away from the discontinuity imposed by a yes vs. no decision: maybe does not exist, because its imple- mentation would be as maybe-yes or maybe-no. Both right and wrong, however arbitrary and nominal, must be allowed to stand long enough to permit the experience cycle to close, starting with a given set of data, hypo- theses, calculations and decisions, and reaching a certain set of observations on the constructed product under operational conditions. Far too much of the modern production of technical literature is con- ditioned by the eureka complex, especially in the respected advanced tech- nological centers. Yet, Man's and Society's time cycle of experience is still deeply conditioned by an animal life cycle, even if somewhat altered by physiological and social evolutions. A house is intended to be a home, and its life cycle should respect a span roughly between twenty and eighty years; public works should serve a couple of generations. It is not only materially but also socially that from the solutions of one generation or period arise the plagues of a following generation. The appropriately named book, Practical Problems in Soil Mechanics and Foundation Engineering by Sanglerat, Olivari and Cambou, comes to fulfill a very important need of thousands of practicing engineers in the geotech- nical profession. It sets a modern, practical milestone for reference, and is almost unique in doing this with its emphasis on calculations, the principal working tool of engineers. The analysis and calculation procedures presented, which encompass the great proportion of geotechnical problems, are simul- taneously both the indication of accepted practice and the reminder that such accepted practice is based on hypotheses: both the hypotheses and the rules developed from them must always be clearly stated, not only so that exceptions may be distinguished, but also so that the consequences of a given practice may be used to establish a modicum statistical universe of VI PREFACE case histories for judging the results achieved and for subsequent iterative adjustment. Solutions in engineering are immediately recognized to be wrong if a patent or catastrophic failure ensues. Time, however, reveals the other extreme of the histogram of failures of engineering solutions, when they conceal a condition of being too safe and relatively less economical than desirable or acceptable. The authors are to be thanked for having offered a good up-to-date reference for appraising both ends of the spectrum. Engin- eers should be enjoined to state clearly the design procedures according to which their projects of a given period were calculated. This book augurs well to stand as a guide for many, many such calculations. VII INTRODUCTION Guy Sanglerat has taught geotechnical engineering at the "Ecole Centrale de Lyon" since 1967. This discipline was introduced there by Jean Costet. Since 1968 and 1970, respectively, Gilbert Olivari and Bernard Cambou actively assisted in this responsibility. They directed laboratory work, outside studies and led special study groups. In order to master any scientific discipline, it is necessary to apply its theoretical principles to practice and to readily solve its problems. This holds true also for theoretical soil mechanics when applied to geotechnical engin- eering. From Costet's and Sanglerat's experiences with their previously published textbooks in geotechnical engineering, which contain example-problems and answers, it became evident that one element was still missing in conveying the understanding of the subject matter to the solution of practical problems: problems apparently needed detailed, step-by-step solutions. For this reason and at the request of many of their students, Sanglerat, Olivari and Cambou decided to publish problems. Over the years since 1967 the problems in this text have been given to students of the "Ecole Centrale de Lyon" and since 1976 to special geotechnical engineering study groups of the Public Works Department of the National School at Vaulx-en-Velin, where Gilbert Olivari was assigned to teach soil mechanics. In order to assist the reader of these volumes, it was decided to categorize problems by degrees of solution difficulty. Therefore, easy problems are preceded by one star (*), those considered most difficult by 4 stars (****). Depending on his degree of interest, the reader may choose the types of problems he wishes to solve. The authors direct the problems not only to students but also to the practicing Civil Engineer and to others who, on occasion, need to solve geo- technical engineering problems. To all, this work offers an easy reference, provided that similarities of actual conditions can be found in one or more of the solutions prescribed herein. Mainly, the S.I. (Systfeme International) units have been used. But, since practice cannot be ignored, it was deemed necessary to incorporate other widely accepted units. Thus the C.G.S. and English units (inch, foot, pounds per cubic foot, etc.) have been included because a large quantity of literature is based on these units. The authors are grateful to Mr. Jean Kerisel, past president of the Inter- national Society for Soil Mechanics and Foundation Engineering, for having VIII INTRODUCTION written the Preface to the French edition and allowing the authors to include one of the problems given his students while Professor of Soil Mechanics at the "Ecole Nationale de Ponts et Chaussees" in Paris. Their gratitude also goes to Victor F.B. de Mello, President of the International Society for Soil Mechanics, who had the kindness to preface the English edition. The first problems were originally prepared by Jean Costet for the course in soil mechanics which he introduced in Lyon. Thanks are also due to Jean-Claude Rouault of "Air Liquide" and Henri Vidal of "Reinforced Earth" and also to our Brazilian friend Lucien Decourt for contributing problems, and to Thierry Sanglerat for proofreading manu- scripts and printed proofs. XIII NOTATIONS The following general notations appear in the problems: A : Skempton's second coefficient (sometimes A refers also to cross-sectional area), value of A at failure Β footing width (sometimes Β refers also to Skempton's first coefficient). c soil cohesion (undifferentiated) c t effective cohesion c ft reduced cohesion (slope stability) undrained cohesion consolidated-undrained cohesion c compression index c uniformity coefficient, defined as d /d 60 l0 coefficient of consolidation d soil particle diameter (sometimes: horizontal distance between adjacent, similar structures, as in the case of sub- surface drains) equivalent diameter of sieve openings in grain-size distri- bution D depth to bottom of footings (sometimes D refers to depth to hard layer under the toe of a slope), void ratio (sometimes: e refers to eccentricity of a concen- trated force acting on a footing) maximum and minimum void ratios ^max > ^min Ε Young's modulus £ pressuremeter modulus P FR friction ratio (static penetrometer test) g acceleration due to gravity (gravie) G shear modulus h hydraulic head Ç soil layer thickness (or normal cohesion: Ç = c cot ö) hydraulic gradient critical hydraulic gradient 'c IP plasticity index k coefficient of permeability k ay > ,avq > ,avc active earth pressure coefficients due to overburden, sur- charge and cohesion, respectively XIV NOTATIONS , fepq, fepc : passive earth pressure coefficients K*Y > ^aq > ^ac :active earth pressures perpendicular to a given plane K^y , pq, ifpc : passive earth pressures perpendicular to a given plane fes : soil reaction modulus Κ : bulk modulus (X s of soil structure, KW of water) K : coefficient of earth pressure at rest 0 I : width of an excavation L : length of an excavation mv : coefficient of compressibility Mm : driving moment MR : resisting moment Ì : bending moment ç : porosity ç¼ : stability coefficient (slope stability problems) Ny, , iVc : bearing capacity factors for foundation design Ρ : concentrated (point) load ñ Õ : limit pressure (pressuremeter test) Pf : creep pressure (pressuremeter test) q : uniformly distributed load (or percolation discharge) Q : discharge (or load acting upon a footing) Qf : friction force of pile shaft (total skin friction force) Qp : end-bearing force of pile (total) qd : ultimate bearing capacity of soil under a footing or pile Qad : allowable bearing capacity of a footing or pile R : radius of a circular footing (or radius of drawdown of a well) RD : relative density (em ax - e)/(emax - emin) r : well radius (or polar radius in polar coordinate system) i?p or qc : end-bearing on the area of a static penetrometer (cone resistance) s : curvilinear abscissa (or cross-sectional area of a thin wall tube, or settlement) S : cross-sectional area of a mold or a sample S. G. : specific gravity St : degree of saturation t : time Ô : shear Tv : time factor u : porewater pressure U : degree of consolidation (or resultant of pore-water pressure forces) í : rate of percolation V : volume W : weight of a given soil volume NOTATIONS XV w : water content or settlement wu wp : liquid limit, plastic limit x,y,z : Cartesian coordinates, with Oz usually considered the verti- cal, downward axis a : angle between orientations, usually reserved for the angle between two crystal faces. Also used to classify soils for the purpose of their compressibility from static cone penetro- meter test data C.P.T. â : slope of the surface of backfill behind a retaining wall (angle of slope) 7 : unit weight of soil (unspecified) 7 : soil particles unit weight (specific gravity) S 7 : saturated unit weight of soil sat 7 : wet unit weight of soil h 7W : unit weight of water = 9.81 kN/m 3 . 7 : dry unit weight of soil d 7' : effective unit weight of soil Txy, 7yZ 5 Tzx · shear strain, twice the angular deformation in a rectangular, 3-dimensional system δ : angle of friction between soil and retaining wall surface in passive or active earth pressure problems, or the angle of inclination of a point load acting on a footing 77 : dynamic viscosity of water ex,ey,ez : axial strains in a rectangular, 3-dimensional system 6j, e2, e3 : principal stress ev : volumetric strain θ : angle of radius in polar coordinates system (sometimes: temperature) í : Poisson's ratio σ' : effective normal stress ï : total normal stress σχ, oy, σζ : normal stresses in a rectangular, 3-dimensional system σι? σ2»σ3 m: ajor principal stresses om : average stress r : shear stress : average shear stress ' m : shear stresses in a rectangular, 3-dimensional system ö : angle of internal friction (undefined) ö : effective angle of internal friction ö" : reduced, effective angle of internal friction (slope-stability analyses) <pcu : angle of internal friction, consolidated, undrained λ : slope of a wall from the vertical ùâ, ùä : auxiliary angles defined by sin ù â = sin β/sin ö and sin co δ = sin δ/sin ö