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TitleSoil Mechanics Fundamentals and Applications
File Size7.2 MB
Total Pages420
Table of Contents
                            Front Cover
Contents
Preface to the First Edition
Preface to the Second Edition
The Authors
Chapter 1: Introduction
Chapter 2: Physical Properties of Soils
Chapter 3: Clays and Their Behavior
Chapter 4: Soil Classification
Chapter 5: Compaction
Chapter 6: Flow of Water through Soils
Chapter 7: Effective Stress
Chapter 8: Stress Increments in Soil Mass
Chapter 9: Settlements
Chapter 10: Mohr’s Circle in Soil Mechanics
Chapter 11: Shear Strength of Soils
Chapter 12: Lateral Earth Pressure
Chapter 13: Site Exploration
Chapter 14: Bearing Capacity and Shallow Foundations
Chapter 15: Deep Foundations
Chapter 16: Slope Stability
Numerical Answers to Selected Problems
Back Cover
                        
Document Text Contents
Page 1

w w w . c r c p r e s s . c o m

K23771

6000 Broken Sound Parkway, NW
Suite 300, Boca Raton, FL 33487
711 Third Avenue
New York, NY 10017
2 Park Square, Milton Park
Abingdon, Oxon OX14 4RN, UK

an informa business

w w w . c r c p r e s s . c o m

Soil Mechanics
Fundamentals
and
Applications

Second Edition

Isao Ishibashi
Hemanta Hazarika

Soil M
echanics Fundam

entals
and Applications

Ishibashi • Hazarika

Second
Edition

ENGINEERING-CIVIL

Soil Mechanics Fundamentals
and Applications Second Edition

“Overall, this book is written in an easy-to-read style suitable for undergraduate
civil engineering students. Chapter one is an excellent example of that style. In just
a few pages, Chapter one provides the reader with an appreciation for geotechnical
engineering and its evolution. It succinctly makes the point that soils are different
from other civil engineering materials, and thus gives students a reason and
purpose for studying the behavior of soils in a stand-alone course.”
—Charles E. Pierce, Ph.D, The University of South Carolina, Columbia, USA

How Does Soil Behave and Why Does It Behave That Way?

Soil Mechanics Fundamentals and Applications, Second Edition effectively
explores the nature of soil, explains the principles of soil mechanics, and examines
soil as an engineering material. This latest edition includes all the fundamental
concepts of soil mechanics, as well as a complete introduction to geotechnical
engineering, including coverage of shallow and deep foundation design and slope
stability. It presents the material in a systematic, step-by-step manner, and contains
numerous problems, examples, and solutions.

New to the Second Edition:

The revised text expands the contents to include an introductory foundation engi-
neering section to make the book cover the full range of geotechnical engineering.
The book includes three new chapters: Site Exploration, Deep Foundations, and
Slope Stability.

Soil Mechanics Fundamentals and Applications, Second Edition is a concise
and thorough text that explains soil’s fundamental behavior and its applications to
foundation design and slope stability and incorporates basic engineering science
knowledge with engineering practices and practical applications.

Page 210

184 Soil Mechanics Fundamentals and Applications

its geological history. This soil is called overconsolidated soil. The e-log σ curve
starts from Point O with the consolidation stress with 0,maxσ (historical maxi-
mum effective overburden stress), and a portion of the stress has been reduced to
Point A (current 0). Note that its historical maximum stress cannot be seen visu-
ally at the present time. Similarly, the sampling process follows A to B and the
laboratory loading process goes from B, C, and D. Preconsolidation stress found
on the laboratory e-log σ curve at Point C is similar to the value of the historical
maximum effective overburden stress .0,maxσ The removal of consolidation stress
from 0,maxσ to 0σ is due to meltdown of glacial ice, excavation, erosion of top soils,
permanent rise of ground water tables, etc. In particular, past glacial ice loads that
covered the North American continent resulted in heavily overconsolidated soils
in the region.

Overconsolidation ratio (OCR) is defined as

OCR
historical maximum effective overburden stress

current effective overburden stress
0,max

0

= =
σ
σ

(9.26)

The OCR value for normally consolidated soils is 1.0, and it is higher than 1.0 for
overconsolidated soils.

Exercise 9.5

In a northern city in the United States, the area had been covered with a 100 m
thick ice load in an early historical time. Some soil in the city is obtained from
10 m deep below the ground surface. The water table was near the ground surface.

CB

E

D

A

Vo
id

R
at

io
, e

log σ

Preconsolidation stress, σc

In-situ effective
overburden stress, σ'0

O

Historical max. effective
overburden stress, σ'0,max

FIGURE 9.14 e-log σ curve for overconsolidated soils.

Page 211

185Settlements

Estimate the value of OCR for this soil specimen. Assume that the area had not
been subjected to any major erosion or excavation.

SOLUTION

Assume that soil’s unit weight is 19 kN/m3 and that ice’s unit weight is the same as
that of water (9.81 kN/m3); thus,

= 9.81 100 (19 9.81) 10 981 91.9 1073 kPa0,maxσ × + − × = + =

= 19 9.81 10 91.9 kPa0 ( )σ − × =

←←σ σ = 11.7Thus, OCR = / = 1073/91.90,max 0

Like the example in Exercise 9.5, many soils in the northern regions of the
United States and Canada are heavily overconsolidated due to the historical glacial
ice load. This created unique soil properties. For example, glacial till is a highly
compacted mixture of gravel, sand, silt, and clay (glacier-carried and -deposited
materials) that has an excellent bearing capacity for foundations. However, since
the lateral stress has not been relaxed as much as the vertical stress upon release of
the ice load, there are rather high lateral stresses trapped in the soil elements. This
creates rather high lateral stress against earth structures. Also, when the area is
excavated or slopes are cut, relaxation in the lateral stress causes gradual increase
of the volume (swelling), and thus the water migrates into the soil elements to
make weaker soil zones, which may possibly lead to gradual failure (creep failure)
of the slope.

Normally consolidated and overconsolidated soils show quite different behaviors
in many aspects, such as shear strength, settlement, swell, lateral earth pressure,
etc., and thus identification of σc relative to 0σ is an important practice during the
consolidation data analyses.

9.10 FINAL CONSOLIDATION SETTLEMENT FOR THIN CLAY LAYER

Assume that a relatively thin clay layer with total thickness of H is subjected to an
incremental stress Δσ due to a new footing, and that its initial vertical effective stress
is 0σ at its mid-depth as seen in Figure 9.15. Final primary consolidation settlement
can be computed as follows.

9.10.1 normaLLy consoLidaTed soiLs

As shown in Figure 9.16, 0σ and 0σ + Δσ are on the virgin curve, and its slope is Cc.
In this case, Equation (9.24) is used to calculate Δe as

e e e C logi c
0

0

= − =
σ + σ
σ

(9.27)

Page 419

w w w . c r c p r e s s . c o m

K23771

6000 Broken Sound Parkway, NW
Suite 300, Boca Raton, FL 33487
711 Third Avenue
New York, NY 10017
2 Park Square, Milton Park
Abingdon, Oxon OX14 4RN, UK

an informa business

w w w . c r c p r e s s . c o m

Soil Mechanics
Fundamentals
and
Applications

Second Edition

Isao Ishibashi
Hemanta Hazarika

Soil M
echanics Fundam

entals
and Applications

Ishibashi • Hazarika

Second
Edition

ENGINEERING-CIVIL

Soil Mechanics Fundamentals
and Applications Second Edition

“Overall, this book is written in an easy-to-read style suitable for undergraduate
civil engineering students. Chapter one is an excellent example of that style. In just
a few pages, Chapter one provides the reader with an appreciation for geotechnical
engineering and its evolution. It succinctly makes the point that soils are different
from other civil engineering materials, and thus gives students a reason and
purpose for studying the behavior of soils in a stand-alone course.”
—Charles E. Pierce, Ph.D, The University of South Carolina, Columbia, USA

How Does Soil Behave and Why Does It Behave That Way?

Soil Mechanics Fundamentals and Applications, Second Edition effectively
explores the nature of soil, explains the principles of soil mechanics, and examines
soil as an engineering material. This latest edition includes all the fundamental
concepts of soil mechanics, as well as a complete introduction to geotechnical
engineering, including coverage of shallow and deep foundation design and slope
stability. It presents the material in a systematic, step-by-step manner, and contains
numerous problems, examples, and solutions.

New to the Second Edition:

The revised text expands the contents to include an introductory foundation engi-
neering section to make the book cover the full range of geotechnical engineering.
The book includes three new chapters: Site Exploration, Deep Foundations, and
Slope Stability.

Soil Mechanics Fundamentals and Applications, Second Edition is a concise
and thorough text that explains soil’s fundamental behavior and its applications to
foundation design and slope stability and incorporates basic engineering science
knowledge with engineering practices and practical applications.

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