Rock and Soil Mechanics

727 Pages·1989·83.798 MB·1-719\727

by  WŁODZIMIERZ DERSKI, RYSZARD IZBICKI, IGOR KISIEL and ZENON MRÓZ (Eds.)

Further Titles in The Series:
1. G. SANGLERAT —THE PENETROMETER AND SOIL EXPLORATION
2. Q. ZÄRUBA 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. ZÄRUBA 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. CA. BAAR —APPLIED SALT-ROCK MECHANICS, 1
The In-Situ Behaviour 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. Ä. KgZDI — 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. Z. BA2ANT—METHODS OF FOUNDATION ENGINEERING
25. Ä. KiZDI —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 —CANALS AND RIVER LEVIES
30. J. FEDA —MECHANICS OF PARTICULATE MATERIALS
THE PRINCIPLES
31. Q. ZÄRUBA AND V. MENCL—LANDSLIDES AND THEIR CONTROL
SECOND, COMPLETELY REVISED EDITION
32. I.W. FARMER (Editor) — STRATA MECHANICS
(continued on p. 720)
DEVELOPMENTS IN GEOTECHNICAL ENGINEERING VOL. 48
ROCK AND SOIL
MECHANICS
by
WLODZIMIERZ DERSKI, RYSZARD IZBICKI, IGOR KISIEL, ZENON MROZ
Institute of Fundamental Technological Research
Polish Academy of Sciences
Warsaw, Poland
Institute of Geotechnics
Technical University
Wroclaw, Poland
ELSEVIER
Amsterdam — Oxford — New York — Tokyo
PWN — POLISH SCIENTIFIC PUBLISHERS
Warsaw
1989
Revised and enlarged translation of the Polish original Mechanika techniczna, t, VII, Mechanika
skal i gruntow published in 1982 by Panstwowe Wydawnictwo Naukowe, Warszawa
Translated by Jolanta Krauze (Chapter VI by Maria Weres)
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Library of Congress Cataloging-in-Publication Data
Mechanika skal i gruntow. English.
Rock and soil mechanics.
(Developments in geotechnical engineering; 48)
(Mechanika techniczna; t. 7)
Translation of: Mechanika skal i gruntow.
Bibliography: p.
Includes index.
1. Rock mechanics. 2. Soil mechanics. I. Derski, Wlodzimierz. II. Title
ΠΙ. Series. IV. Series: Mechanika techniczna; t. 7.
TA706.M413 1988 624.Γ513 87-15534
ISBN 0-444-98950-1 (U.S.)
ISBN 0-444-41662-5 (series)
Copyright (g) by PWN—Polish Scientific Publishers—Warszawa, 1989
All rights reserved. No part of this publication may be reproduced, stored in retrieval system or
transmitted in any form or by any means, electronic, mechanical, photocopying, recording or
otherwise, without the prior written permission of the copyright owner
Printed in Poland
Preface
Among numerous works devoted to the theoretical foundations of soil mechanics
two are worthy of special mention: K. Terzaghi's Theoretical Soil Mechanics published
in New York in 1948, and W. A. Florin' sFundamentals of Soil Mechanics published
in Moscow in 1961 (in Russian), for both o fthem cover the entirety of the problems
that are the subject of interest of Soil Mechanics. Since the publication of the latter
book, several new computation methods and solutions have been developed and
numerous new proposals made, which may find application in soil mechanics, such
as, to mention only a few, the application of rheology in describing soil behaviour
under average conditions, the improvements in Biot's consolidation theory as applied
to the determination of the settlement processes under building structures, further
progress in the limit state methods which have been much advanced since the days
of Terzaghi and Sokolovsky, and, finally, several proposals concerned with a theor-
etical explanation of the phenomena associated with loading of clays. Moreover,
during the last few decades a new discipline has been rapidly developed and become
generally accepted: Rock Mechanics which at present may boast considerable
achievements.
In the view of the authors, rock and soil mechanics is a discipline that attempts
to apply the theory of continuum to the mechanical investigation of rock and soil
media. This approach does not, of course, mean that we exclude certain mechanical
solutions resulting from the specific character of the media investigated. Rocks and
soils are formations made by nature and are only "found" by man who wishes to
use them for his own purposes. Thus we do not try to form them in accordance
with our desires but take advantage of the properties that are available at a given
place. That is why so many, and such diverse methods for the mechanical approach
to rocks and soils have been developed since the day when, in 1925, K. Terzaghi
created a new discipline and called it soil mechanics.
The present book is composed of two separate parts. Part one, embodying the
first three chapters, is devoted to a description of the media of interest. Chapter 1,
which is an introduction to the main argument, discusses the essence o fthe discipline
and its links with other branches of science that are concerned, on the one hand,
with technical mechanics, and, on the other, with the properties, origins, and forma-
tion of rock and soil strata under natura flield conditions. Rocks and soils differ from
VI PREFACE
the media studied in mechanics of continuum in that they are discontinuous, disin-
tegrated, and have a multicomponent structure.
In Chapter 2 we describe the mechanical models of bodies that are useful for the
purposes of our discourse. These are: rheology of continuum, including the theory
of isotropic and anisotropic elasticity, linear rheology, Terzaghi's hydrodynamic
model which forms the basis for the present-day consolidation theory, and, finally,
discrete models which serve to describe soils and rocks in terms of mechanics. Finally*
this chapter defines the concept of the limit shear resistance of soils and rocks, which
is one of their most characteristic properties.
Chapter 3 presents the actual properties of soils and rocks as determined from
experiments in laboratories and in situ. Several tests used in geotechnical engineering
are described, and interconnections between the physical state of rocks and soils
and their rheological parameters, in a broad sense of this term, are considered.
Some information on frozen soils is also given, in view of the wide-spread use,
particularly in Poland, of freezing techniques in constructing mining shafts.
The second part of the book considers the applications of various theories which
either were first developed for descriptive purposes in continuum mechanics and
then adopted in soil and rock mechanics, or were specially developed for the latter
discipline. Chapter 4 discusses the application of the theory of linear viscoelasticity
(including the theory of elasticity) in solving problems of stable behaviour of rocks
and soils. Several fundamental solutions are given and some aspects of the investiga-
tion of the state of stress and the state of strain are discussed in relation to open
excavations or drifts and shafts made inside rock and soil strata. Some solutions are
also proposed to basic problems associated with discrete models of rocks and soils.
Chapter 5 deals with the use of the groundwater flow theory as applied to several
problems connected with water movements in an undeformable soil or rock skeleton.
Among other effects, this movement may cause seepage forces to act on the skeleton,
which may have unfortunate consequences if ignored. Furthermore, some drainage
problems in soil and rock strata, especially those essential in strip mining and con-
structing hydrotechnical objects, are also discussed.
Chapter 6 is a natural expansion of the arguments put forward in the previous
chapter. Here the movement of water is regarded as the cause of deformation of the
rock or soil skeleton. The consolidation theory developed on this basis is here pre-
sented in a novel formulation, which differs from the formulations found in the
literature on the subject. Some new engineering solutions, mainly those developed
in Poland during the last decades, are reported.
Chapter 7, the longest, is devoted to the limit state theory as applied to the study
of the mechanical behaviour of soils and rocks. Here also some new (among them
Polish) solutions and methods are presented, which include both static and kinematic
aspects of the problem; this approach makes possible a more correct estimate than
that based only on statics of the behaviour of granular media under the action
of considerable mechanical forces. This chapter also indicates the relations between
PREFACE VII
what are called the "engineering" methods of computing the stability of slopes
and the theoretically correct solution based on the limit state theory including
a simultaneous evaluation of the upper safety limit. This chapter also presents
some original effective methods for investigating media of limited cohesion.
Chapter 8, the last, is an attempt to provide a systematic account of the mechanics
of highly dispersed soils, commonly called clays. The literature on clays is suprisingly
rich; there has been no attempt so far however to classify the characteristic features
of clays and their response to load. The present book is thus the first attempt at such
an approach; whether this is successful or not is for the reader to decide.
Although the book was designed to be encyclopedic, even with its considerable
length, it was not possible to include all the ideas and methods deserving of attention.
It is, of course, the authors who bear responsibility for the selection of the subject
material. They wished, first of all, to include such methods and problems which
may already find direct or indirect practical applications. But for any method to be
used in geotechnical engineering practice it is required that the numerical data
available on the characteristic parameters of soils and rocks be fully reliable, which
means that they should be based on a great number of experiments. Such data are
available only for linearly deformable media, for Coulomb's theory of the limit
state, and for groundwater flow in soils. This is the reason why it is just those methods
which have been given most attention in the present book. The entire huge and
promising domain of non-linear solutions has had to be omitted, mainly because
of lack of credible data regarding the parameters involved, characteristic of non-
linear media. Although the present book has a theoretical character the authors
intended it to be a source of information for those involved in practical problems.
Finally, a few words about the notations employed. Basically, we use the notations
commonly adopted in the literature on the mechanics of deformable continuum.
The notations typical for Geotechnical Engineering are consistent with those recom-
mended in the List of Symbols published by ISSMFE in 1978. The sole exception
is the symbol used to denote pore pressure; to avoid misunderstanding, instead
of the symbol u recommended in the List of Symbols we consistently use the symbol
a since in the mechanics of continuum u denotes the displacement of a current
w
point of a deformable medium.
We wish to thank Dr. A. Dreszer for his invaluable comments during the prep-
aration of the manuscript, our translator Jolanta Krauze, and the publishers for
all work connected with the preparation of the present edition. We are also indebted
to all the authors whose works contribute to the material gathered in this book.
On behalf of the contributors
IGOR KISIEL
List of frequently used symbols
A area, Biot's consolidation constant (Chapter 6)
b width
C i tensor of elastic constants
iJk
c cohesion
d diameter
E i tensor of moduli of elasticity (Young's moduli)
ijk
Gijkt tensor of moduli of elasticity (Kirchhoff's moduli)
h height, thickness
K coeflScient of permeability [m2], operator of volume rigidity
k Darcy's coeflScient (seepage coeflScient)
L operator of shear rigidity
N Biot's consolidation constant (Chapter 6)
n volumetric porosity
n surface porosity
A
Q Biot's consolidation constant
R Biot's consolidation constant, strength of material
r radius, polar coordinate
T temperature, relaxation time
/ time
u displacement of solid particles (soil skeleton)
V volume
v displacement of fluid particles
vv soil moisture (water content in soil)
€ij tensor of infinitesimal strain
ε volumetric strain
0
e void ratio
η modulus of shear viscosity
e deviator of infinitesimal strain
i$
k plasticity limit
modulus of volume elasticity
v Poisson's ratio (y < 0.5)
γ unit weight
Oij stress tensor
LIST OF FREQUENTLY USED SYMBOLS IX
σ isotropic stress (average)
0
a groundwater pressure (pore pressure) — symbol used instead of u recommended
w
in ISSMFE "List of symbols, units and definitions"
Sij stress deviator
φ angle of internal friction in soils
my tensor of infinitesimal rotation
r shear stress due to preconsolidating pressure
f
τ/ shear stress due to friction
τ" shear stress due to viscous flow
Tmax shear stress acting in the past
0 flow limit
All other symbols not listed above are specified in the text.
Note: The indices i j k, I assume the values 1, 2, 3.
99
1. Definition and subject of the discipline
1.1 Nature of the discipline and interdisciplinary connections
1.1.1 Introduction
Soils and rocks make up that part of the Earth's crust where the life and activities
of man have developed. The thickness of the Earth's crust now accessible to this
activity is about 10 km. It consists mainly of mineral formations created at various
geological periods, from the Precambrian (over 3.5 milliard years ago) to the Quater-
nary period (1.5 million years ago up to the present). The history of the Earth, its
structure and presumable composition, the processes by which the Earth has under-
gone and is still undergoing transformations, the origin and history of rock and
soil strata, all these are the subject of study of the science of geology.
Investigation of the thermo-rheological properties of rocks and soils, and solution
of the mechanical problems connected with engineering works on the surface of the
Earth's crust and deep inside it are the province of soil and rock mechanics.
The task of rock and soil mechanics as formulated above is the same as that
of the other branches of mechanics; therefore it would be superfluous to distinguish
rock and soil mechanics as a separate branch of engineering mechanics.
However, rock and soil media exhibit discontinuities both in the geometrical
and in the physical sense: geometrical, because rock masses are broken by layering
and joints into separate blocks and strata; physical, since the properties of the
material often vary significantly from place to place in a given massif.
These discontinuities affect the medium in an essential manner as regards its
ability to respond and the way it responds to disturbances of its natural state (further
referred to as the in situ state), and thus must never be ignored. Moreover, rock
soil media do not, in practice, exist in their natural state, i.e. free of internal forces
and deformations; at the time of examination they almost always show residual
stresses and deformations resulting from forces which acted in a remote geological
past and which affect in an essential way the mechanical phenomena which are
being investigated.
Although rock and soil mechanics utilizes the whole output of the mechanics
of continuous media, it uses its own approach to the matter by:
(a) allowing directly or indirectly for the discrete structure of a rock or soil
medium, and
2 1. DEFINITION AND SUBJECT OF THE DISCIPLINE
(b) taking into account the multicomponent structure of rock and soil media,
i.e. the fact that every soil or rock includes water (or another fluid, such as for instance
mineral oil) as well as a gas (air, natural gas, etc.).
In order to solve the particular problems arising in engineering practice, rock
and soil mechanics must make use of the results of the following scientific disciplines:
— physics and chemistry, which can explain a number of phenomena that
occur in rocks and soils that affect their mechanical properties, particularly if the
rock or soil examined is very fine-grained (dispersed),
— geology and allied sciences, which permit an adequate geometrical and histo-
rical description of the strata under investigation.
1.L2 Problems of rock and soil mechanics
The problems rock and soil mechanics has to face may be divided into the follow-
ing main groups:
1. Problems whose solutions answer some particular engineering questions,
such as the pressure of a mass of rock or soil on the excavation brace, scarp or slope
stability, distribution of pressure exerted on a rock stratum by building structures,
displacements of the ground surface due to failure of previously made underground
excavations or spontaneous movements inside a stratum resulting from the activity
of man.
2. Problems whose solutions give answers to particular geological questions and
aim at explaining the origins of various geological forms encountered in nature,
such as, for example, elements of the local structure of strata (slides, faults), and
at a theoretical explanation of stress fields observed in strata, of the mechanism
of mountain building, movements of continents, etc.
3. Problems concerning the methods of investigating rocks and soils and explaining
some processes characteristic for them, such as methods of comparing thermo-
rheological parameters measured on small size specimens with those measured
in rock strata, of the determination of the criteria used to identify rock or soil destruc-
tion and the mechanisms of this destruction, of the simulation of local geological
phenomena, particularly tectonic activities, etc.
1.1.3 Methods used in rock and soil mechanics
To solve the problems described in Section 1.1.2, rock and soil mechanics makes
the following assumptions:
(a) rock and soil media are continuous, their discontinuities and granularity
thus being neglected, which enables us to make direct use of all the solutions and
all the experimental methods of the mechanics of continuous media;
(b) a continuous medium has a multicomponent structure, which means that
it consists of two or three mutually penetrating materials which are in different
states of aggregation: solid, liquid, or gaseous.