Table Of ContentFurther titles in this series :
Volumes 1, 2 and 3
are out of print
4. R. SILVESTER
COASTAL ENGINEERING, I and II
5. R.N. YOUNG 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. VOIGT (Editor)
ROCKSLIDES AND AVALANCHES, 1 and 2
15. C. LOMNITZ AND E. ROSENBLUETH
SEISMIC RISK AND ENGINEERING DECISIONS
16A. C.A. BAAR
APPLIED SALT-ROCKS MECHANICS, I
The in-situ Behavior of Salt Rocks
17. A.P.S. SELVADURAI
ELASTIC ANALYSIS OF SOIL-FOUNDATION INTERACTION
18. J. FED A
STRESS IN SUBSOIL AND METHODS OF FINAL SETTLEMENT CALCULATION
19. A. KÉZDI
STABILIZED EARTH ROADS
20. E.W. BRAND AND R.P. BRENNER
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
Developments in Geotechnical Engineering 24
METHODS
OF FOUNDATION
ENGINEERING
by
ZDENËK BAZANT
Professor of Civil Engineering,
Technical University in Prague
and Geotechnical Consultant,
Geoindustria, Prague, Czechoslovakia
ELSEVIER SCIENTIFIC PUBLISHING COMPANY
Amsterdam · Oxford · New York · 1979
Scientific Editor
Prof. Ing. Dr. Konrad Hruban, DrSc.
Corresponding Member of the Czechoslovak Academy of Sciences
Reviewer
Doc. Ing. Zdenêk Sobotka, DrSc.
Published in co-edition with
ACADEMIA, Publishing House of the Czechoslovak Academy of Sciences,
Prague
Distribution of this book is being handled by the following publishers
for the U.SA. and Canada
Elsevier/North Holland, Inc.,
52 Vanderbilt Avenue
New York, New York 10017
for the East European Countries, China, Northern Korea,
Cuba, Vietnam and Mongolia
Academia, Publishing House of the Czechoslovak Academy of Sciences, Prague
for all remaining areas
Elsevier Scientific Publishing Company
335 Jan van Galenstraat
P.O. Box 211, 1000 AE Amsterdam, The Netherlands
Library of Congress Cataloging in Publication Data
Bazant, Zdenëk.
Methods of foundation engineering.
(Developments in geotechnical engineering; 24)
Updated and revised translation of Metody zaklâdâni staveb.
Bibliography: p.
Includes indexes.
1. Foundations. I. Title. II. Series.
TZ775.B3713. 624U5 78-15933
ISBN 0-444-99789-X (Vol. 24)
ISBN 0-444-^1662-X (Series)
© Zdenêk Bazant, Prague 1979
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or trans-
mitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise,
without the prior written permission of the publishers
Printed in Czechoslovakia
PREFACE
The book presents a review of the state of the art in the theory, analysis, and
practice of foundation engineering, and its soil mechanics and structural design
aspects and principles. It attempts to meet the needs of practicing engineers who
are called upon to solve the vital problem of selecting a suitable foundation method,
an indispensable condition of success of any foundation project.
The book aims to discuss the design of foundations under ordinary circumstances.
Therefore the form of the presentation is deliberately clear, concise and simple,
and an attempt has been made to write the book bearing in mind Blaise Pascal's
remark: "The best books are those which every reader thinks he himself could
have written" (On the Art of Persuasion, or Eloquence). It tries also to adopt an
impartial point of view, giving no preference to particular methods. The treatment
of the subject matter is analytical, with attention accorded to principles rather than
to case histories. Ample references are provided to enable the reader to gain detailed
information on his more complex problems.
The book is divided into five parts. Part A is of an introductory character and
presents a brief review of the various types of foundation structures used in civil
engineering and their historical development. Part Β provides the theoretical
fundamentals of soil and rock mechanics which are of importance for foundation
design. Part C deals with the design of the footing area of spread footings and discusses
the shallow foundation methods. Part D describes the methods of deep foundations,
and Part Ε is devoted to special foundation methods.
In Parts C through E, which form the main theme of the book, each chapter starts
with an introduction containing a synopsis of the matter being discussed and giving
suggestions as to the choice of a suitable method of foundation. This is followed
by a description of the methods generally used in practice. Simple analyses of struc-
tures, presented at the conclusion of each chapter, can be carried out by a pocket
calculator (or a slide rule). Because of uncertainties involved in ascertaining the
realistic values of soil properties, this technique can be regarded as satisfactory
for the majority of practical foundation designs. Although the cases likely to be
encountered in general practice are comparatively straightforward and their closed
form solutions can be obtained by means of simple calculations, complex problems,
research, and the handling of a large number of'solutions call for the application
6 PREFACE
of large computers. Several references to computer programs associated with
geomechanics problems are, therefore, also included in the book.
The field of foundation engineering is so broad that it can hardly be covered
in a single volume. For this reason, the Czech original is supplemented by two other
publications; namely, a book entitled "Foundation Engineering Problems"
(Bazant 1966), which describes the case histories of basic foundation structures,
and a textbook (Bazant 1967, 2nd. Edn.) which contains numerical examples whose
solutions are based on Czechoslovak Standards. Since these examples are worked
out in accordance with the stipulations of the respective Czechoslovak Standards,
and, as such, are of no use in other countries, they are not included in the English
version.
Although foundation engineering, thanks to advances in soil mechanics, has been
tending to achieve the status of a science, it continues to be an art rather than a
scientific discipline and a correct solution of foundation problems is still largely
a matter of experience and judgment. The possibilities of soil mechanics and, es-
pecially, of rock mechanics do not permit the foundation soils — which are by nature
nonhomogeneous — to be treated with the same precision as do the more homo-
geneous steel or concrete structures. Hence, the calculations should be supplemented
by a sound estimate of the conditions encountered in the field, and these conditions
always differ from the theoretical simplified schemes used in soil mechanics. Since
the actual approach used in making major decisions is based more on empirical
knowledge than on calculations, each design involves a certain risk. To decide how
far the engineer is justified in assuming such a risk, is a matter of utmost importance.
The author wishes to express his thanks to Professor K. Hruban, who reviewed
two editions of this book in Czech as well as its English version and who has been
most generous in offering valuable advice and suggestions concerning clarification
of some of the paragraphs. He is also indebted to Geoindustria, Prague, the company
he joined after his retirement from the Technical University of Prague, for providing
him with the time needed to finish the manuscript.
The author dedicates this book to his wife, without whose encourangement and
helpful assistance the task of writing would have been much more difficult.
Zdenêk Bazant
SYMBOLS
The following symbols are used throughout the text. Soil mechanics symbols
conform to the recommendations of the International Society for Soil Mechanics
t
and Foundation Engineering as published in Special Bulletin A of the Eighth
International Conference, Moscow, 1973. Symbols used sporadically are not included
in this list.
a length
A area; reaction
Β width
c total cohesion; d effective cohesion; c coefficient of consolidation
v
C resultant cohesion; C circumference (perimeter) of pile
p
d distance; grain diameter; pile or drilled pier diameter; d grain diameter of
l0
10 per cent size
D depth; length of pile; D thickness of i-th stratum
x
e void ratio ; eccentricity
Ε Young's modulus of elasticity; E modulus of deformation
o
/ pole distance; deflection; / ' allowable concrete compressive stress; f yield
c
steel strength
F force; F factor of safety; factor of slope stability
s
g acceleration of gravity; uniform load
G dead weight; specific gravity
h head (hydraulic)
H height; horizontal force; thickness of stratum; H critical height; H thickness
c s
of sample
i hydraulic gradient
J moment of inertia; coefficient; I consistency index; J relative density;
c D
J plasticity index
p
k coefficient of permeability; k coefficient of horizontal subgrade reaction;
h
fc coefficient of vertical subgrade reaction
s
Κ coefficient; coefficient of rigidity; X , K, K earth pressure coefficients
a 0 p
L length; L Mohr's envelope of failure
M
m capacity reduction factor
M moment; M modulus of one-dimensional deformation
o
10
SYMBOLS
η porosity; n constant of horizontal subgrade reaction
n
JV normal component of load; Ν , N, N bearing capacity factors;
q c
N stability number
s
ρ soil pressure; contact pressure
Ρ resultant of pressures; P end-bearing capacity of pile (pier);
e
P negative skin resistance; P positive skin resistance
n p
q uniform contact pressure; q ultimate end-bearing capacity of pile;
Q
q ultimate bearing capacity of soil; q allowable bearing capacity;
f Q
q compressive strength; q ultimate skin friction of pile;
s s
q net bearing pressure
Q shear force; total load; rate of flow; Q ultimate bearing capacity; Q pile
hu c
settlement capacity; Q pile failure load ; β proposed pile capacity; g ultimate
f ρ su
shaft resistance; Q pile bearing capacity; Q ultimate yield load
u yu
r radius
R reaction; resultant of external forces; distance; characteristic length
s final set of pile
S earth pressure; axial load in pile; section modulus; dispersion degree;
S degree of saturation; S' coefficient of contraction
r z
t time
u pore pressure
U uniformity coefficient ; uplift force; U degree of consolidation
c
ν velocity; coefficient of variation
V volume; V allowable pile capacity; V ultimate pile capacity;
Q T
ultimate structural pile capacity
w settlement; vertical deformation; w elastic settlement; w water content in per
e n
cent of dry weight; w liquid limit; w *permissible settlement; w plastic limit;
L p p
w shrinkage limit
s
W weight
χ abscissa
X coordinate axis
y ordinate; deflection
Y coordinate axis
ζ vertical coordinate; depth
Ζ coordinate axis
α angle; coefficient; coefficient of shape and rigidity; adhesion factor
β angle of slope at horinzontal; proportion of the base load
y γ unit weight of dry soil; y unit weight of soil, water in pores included; y unit
ά n s
weight of solid particles; y unit weight of water; y' submerged unit weight
w
δ angle; angle of wall friction
ε linear strain; ε vertical strain
ζ
η coefficient of viscosity; moment arm; mechanical efficiency; reciprocal value
of characteristic length (in sand)
SYMBOLS 11
3 angle of slope
κ coefficient
λ reciprocal value of characteristic length (in clay); λ compressive strain of pile
η
μ μ discharge factor
ζ
ν Poisson's ratio
ξ relative depth
σ stress (total); σ' effective normal stress; σ , a normal stresses on vertical planes;
χ y
σ normal stress on horizontal plane; σ σ , σ principal stresses
ζ ν 2 3
τ shear stress; τ shear strength
{
φ angle; velocity potential
Φ angle of internal friction (total); Φ' effective angle of internal friction
φ angle of angular deflection of beam
CONVERSION FACTORS
The SI units used in this book are those recommended by the International
Standard Organization (ISO) in 1960, introducing the newton [Ν] as the unit of
force.
Conversion of the SI system to the English system
Length lm 3.28 ft = 1.094 yd
1 cm 0.394 in.
1 mm 0.0394 in.
Area lm2 10.8sqft(sf) = 1.196 sq yd
lcm2 0.155 sq in. (si.)
Volume lm3 35.3 cu ft = 1.308 cu yd
11 0.264 gal (USA) = 0.220 gal (Imp)
lcm3 0.061 cu in.
Mass It 1.10 ton = 2.20 kips = 2200 lb
lkg 2.20 lb
Force 1MN 225 kipsf
lkN 225 lbf = 0.225 kipsf
IN 0.225 lbf
Stress 1 MN/m2 1 N/mm2 = 10.45 tsf (short ton per sq ft)
1 kN/m2 0.01045 tsf
1 kN/m2 20.9 psf(lb per sq ft)
1 kN/m2 0.145 psi (lb per sq in.)
Unit weight 0.001 MN/m3 1 kN/m3 = 6.37 psf (lb per cu ft)
IN/: mm~ 3690 pci (lb per cu in.)
Acceleration
of gravity 9.81 m/s2 = 32.2 ft per sec2
CONVERSIONS FACTORS 13
Conversion of the English system to the SI system
Length 1 mile = 1.609 km
1yd = 0.91 m
1ft = 0.305 m = 30.5 cm
lin. = 0.0254 m = 25.4 mm
Area 1 sq mile = 2.59 km2
1 sq yd = 0.836 m2
lsf = 0.0929 m2 = 929 cm2
1 sq in. = 6.45 cm2
Volume 1 cu yd = 0.765 m3
leu ft = 0.0283 m3
1 cu in. = 16.4 cm3
1 Imp gal = 4545 cm3 = 4.551
1 gal (USA) = 3785 cm3 = 3.791
Mass 1 ton (short) = 0.90721 = 907.2 kg
lkip = 0.4541 = 454 kg
lib = 0.454 kg = 454 g
Force 1 ton force (short) = 8.90 kN = 0.0089 MN
1 kip force = 4.45 kN
1 lb force = 4.45 Ν
Stress ltsf = 95.7 kN/m2
lpsf == 00..00447799 kkNN//mm22
1 psi == 66..8899 kkNN//mm22
Unit weight lpcf = 0.157 kN/m3
1 pci = 0.000271 N/mm3
Approximate conversion of the kilopond (kilogramforce) units (Czechoslovak and
Central Europe Standards up to 1974) to newton units used in this book
Force 1 Mp = 10 kN = 0.01 MN
1 kp = 10 Ν (more exactly 9.81 N)
Stress 1 kp/cm2 = 0.1 N/mm2 = 100 kN/m2 = 0.1 MN/m2
Unit weight 1000 kp/m3 = 10 kN/m3 = 0.01 MN/m3
