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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Sprache: Englisch
An overview of the key foundations of soil mechanics
Geotechnical engineering is the subfield of civil engineering which specifically deals with the behavior of earth materials, such as soil and rocks. Soil mechanics is an essential component of geotechnical engineering, and one which incorporates geology, hydrogeology, and other connected subjects in an interdisciplinary engineering approach. Since geotechnical engineering remains a vital component of civil engineering, the need for good introductory materials on soil mechanics continues to be urgent.
Essentials of Soil Mechanics meets this need with a concise, readable introduction to soil behavior and the engineering properties of soil. Written by a practicing engineer with a passion for teaching, it emphasizes content that is used on a regular basis and equips engineers to find additional information they may need. It is an essential reference and supplement for anyone needing additional guidance on this crucial subject.
Essentials of Soil Mechanics readers will also find:
- A friendly, engaging, accessible tone throughout
- Detailed discussion of topics including effective stress, seepage, consolidation, shear strength, and more
- Recaps at the end of each chapter to emphasize key concepts
Essentials of Soil Mechanics is ideal for students studying soil mechanics, geotechnical engineering, civil engineering, and related subjects.
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Seitenzahl: 193
Veröffentlichungsjahr: 2025
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Table of Contents
Cover
Table of Contents
Title Page
Copyright
Symbols
Acknowledgments
About the Companion Website
Introduction
Preview of Chapters
Units
1 Soil Composition
1.1 Phase Diagrams
1.2 Application of Phase Diagrams: Compaction
1.3 Coarse‐ and Fine‐Grained Soils
1.4 Unified Soil Classification System
1.5 Chapter Recap
Problems
Solutions
2 Stresses in the Ground
2.1 Vertical Total Stress
2.2 Pore Water Pressure
2.3 Vertical Effective Stress
2.4 Horizontal Effective Stress
2.5 Horizontal Total Stress
2.6 Mohr Circles
2.7 Stresses in the Ground due to Surface Loads
2.8 Chapter Recap
Problems
Solutions
3 Seepage
3.1 What Causes Seepage
3.2 Seepage‐Related Pore Water Pressures
3.3 Hydraulic Gradient at Points of Interest
3.4 Flow Rate
3.5 Chapter Recap
Problems
Solutions
4 Consolidation
4.1 What Happens During Consolidation
4.2 Magnitude of Consolidation
4.3 Changes in Stress State During Consolidation Loading and Unloading
4.4 Time‐Rate of Consolidation
4.5 Chapter Recap
Problems
Solutions
5 Shear Strength
5.1 The Mohr–Coulomb Failure Line
5.2 Drained and Undrained Loading Conditions
5.3 Example Stability Problem with a Sand Foundation
5.4 Example Stability Problem with a Clay Foundation
5.5 Undrained Shear Strength for Partially Saturated Soils
5.6 Shear Strength for Changes in Groundwater Level
5.7 Chapter Recap
Problems
Solutions
6 Active and Passive Pressures
6.1 Active Pressures
6.2 Passive Pressures
6.3 Summary of Rankine's Theory
6.4 Movements Required for Active and Passive Pressures
6.5 Chapter Recap
Problems
Solutions
7 Site Investigations
7.1 A General Approach to Site Investigations
7.2 An Example Site Investigation
7.3 Chapter Recap
References
Index
End User License Agreement
List of Tables
Chapter 1
Table 1.1 Phase diagram calculations in a compaction test.
Table 1.2 Sieve analysis results for soil
A
.
Table 1.3 Some common USCS classifications.
Chapter 2
Table 2.1 Vertical total stress calculations.
Chapter 3
Table 3.1 Heads at points in Figure 3.1.
Table 3.2 Heads at points in Figure 3.2.
Table 3.3 Permeability ranges for sands from U.S. Army (1983).
Chapter 4
Table 4.1 Dimensionless values of
T
and
U
and calculated values of
t
and
s
....
Chapter 5
Table 5.1 Ranges of friction angle for clean sands.
Chapter 7
Table 7.1 Vertical total stress calculations.
List of Illustrations
Chapter 1
Figure 1.1 Soil particle sizes.
Figure 1.2 Soil phase diagram.
Figure 1.3 Compaction test results.
Figure 1.4 Grain size distributions.
Figure 1.5 Plasticity chart.
Figure 1.6 Deflocculated (left) and flocculated (right) clay particles.
Figure 1.7 Flocculated clay particles with different fabrics.
Figure 1.8 Thin (left) and thick (right) zones of increased cation concentra...
Chapter 2
Figure 2.1 Example soil profile for stress calculations.
Figure 2.2 Plots of stresses (kPa) versus depth (m).
Figure 2.3 Stresses (
σ
,
τ
) on an arbitrary plane at a point in the...
Figure 2.4 Stress conditions in real space.
Figure 2.5 Stress conditions in stress plot space.
Figure 2.6 Another way to find the center of a Mohr circle.
Figure 2.7 Element of soil at a depth of 4 m in Figure 2.1.
Figure 2.8 Stress plot for element of soil in Figure 2.7.
Figure 2.9 Mohr circle for the soil element in Figure 2.7.
Figure 2.10 Effective stress Mohr circle for the soil element in Figure 2.7....
Figure 2.11 Element of soil at a depth below sloping ground.
Figure 2.12 Stress plot for the soil element in Figure 2.11.
Figure 2.13 Mohr circle for the soil element in Figure 2.11.
Figure 2.14 Effective stress Mohr circle for the soil element in Figure 2.11...
Figure 2.15 Vertical stress distributions at depth due to a strip load appli...
Figure 2.16 Generic soil stress–strain curve.
Figure 2.17 Elastic solution for horizontal stresses acting on a rigid wall ...
Chapter 3
Figure 3.1 Hydrostatic condition.
Figure 3.2 Seepage condition.
Figure 3.3 Dimensions of a square in a flow net.
Chapter 4
Figure 4.1 Soil profile for consolidation example.
Figure 4.2 Increases in vertical stress beneath loaded square areas.
Figure 4.3 Consolidation test sketch.
Figure 4.4 Consolidation test results for case
A
.
Figure 4.5 Idealized consolidation curves for case
A
.
Figure 4.6 Consolidation test results for case
B
.
Figure 4.7 Idealized consolidation curves for case
B
.
Figure 4.8 Settlement calculations for case
B
.
Figure 4.9 Soil structure changes during consolidation.
Figure 4.10 Mohr circles for the application and removal of 6‐m tall fill.
Figure 4.11 Consolidation and rebound for the application and removal of Δ
σ
...
Figure 4.12 Mohr circles for the application and removal of 18‐m tall fill....
Figure 4.13 Pore water pressure changes during consolidation.
Figure 4.14 Drainage path length in the consolidation test specimen (left) a...
Figure 4.15 Time‐rate of consolidation curves.
Chapter 5
Figure 5.1 Shear strength mobilized in soil beneath a footing.
Figure 5.2 Mohr–Coulomb failure line.
Figure 5.3 Curved failure envelope with Mohr–Coulomb failure line approximat...
Figure 5.4 Example stability problem.
Figure 5.5
t
99
versus drainage path length.
Figure 5.6 Example change in state of total stress.
Figure 5.7 Volume change tendencies of soils based on density (influence of ...
Figure 5.8 Steep cut in a stiff, saturated clay.
Figure 5.9 Initial and final effective stress conditions at point
a
in the s...
Figure 5.10 Effective stress conditions at point
a
in the sand foundation un...
Figure 5.11 Consolidation conditions and corresponding undrained shear stren...
Figure 5.12 Sketch of the triaxial test apparatus.
Figure 5.13 Stress–strain curve for the example UU triaxial test.
Figure 5.14 Results of UU triaxial tests on saturated clay from point
a
.
Figure 5.15 Mohr–Coulomb failure line for UU triaxial tests on partially sat...
Figure 5.16 Change in groundwater level in a residual clay slope.
Figure 5.17 Map of drained and undrained conditions for
saturated
soils.
Chapter 6
Figure 6.1 Retaining wall that has rotated slightly to the left.
Figure 6.2 Conditions for Rankine's active (upper chart) and passive (lower ...
Figure 6.3 Active pressure distribution and resultant force acting on the wa...
Figure 6.4 Coulomb's method for the active condition.
Figure 6.5 Example curved failure surface in the form of a log‐spiral for th...
Figure 6.6 Buried anchor that has moved to the left.
Figure 6.7 Passive pressure distribution and resultant force acting on the a...
Figure 6.8 Coulomb's method for the passive condition.
Figure 6.9 Example curved failure surface in the form of a log‐spiral for th...
Figure 6.10 Rankine's active and passive pressures.
Chapter 7
Figure 7.1 Plan view of the new tank and building at a wildlife rehabilitati...
Figure 7.2 Preliminary model of subsurface conditions.
Figure 7.3 Exploration plan for the example site.
Figure 7.4 Subsurface profile along line A–A′ in Figure 7.3.
Figure 7.5 Simplified log for boring B3.
Figure 7.6 Grain size distribution for sand from B3, S3.
Figure 7.7 Atterberg limits for clay from B3, S6 on the plasticity chart.
Figure 7.8 Plots of stresses (kPa) versus depth (m).
Figure 7.9 Schematic of the constant head test performed using a piezometer....
Figure 7.10 Consolidation test results for clay from B3, S6.
Figure 7.11 Results of UU triaxial tests on saturated clay from B3, S6.
Guide
Cover
Table of Contents
Title Page
Copyright
Symbols
Acknowledgments
About the Companion Website
Introduction
Begin Reading
References
Index
End User License Agreement
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Essentials of Soil Mechanics
Jeremy BrittonCivil Engineer, Portland DistrictU.S. Army Corps of Engineers Adjunct InstructorPortland State University
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Paperback ISBN: 9781394289875
Cover Design: WileyCover Image: © rawintanpin/stock.adobe.com
Symbols
a
v
Coefficient of compressibility
c
Total stress cohesion intercept
c′
Effective stress cohesion intercept
c
v
Coefficient of consolidation
C
c
Coefficient of curvature (
Chapter 1
) or Compression index (
Chapter 4
)
C
r
Recompression index
C
u
Coefficient of uniformity
D
Maximum drainage path length
D
r
Relative density
e
Void ratio
g
Acceleration of gravity
G
s
Specific gravity of solids
γ
Unit weight
γ
b
Buoyant unit weight
γ
d
Dry unit weight
γ
m
Moist unit weight
γ
sat
Saturated unit weight
γ
t
Total unit weight
γ
w
Unit weight of water
h
e
Elevation head
h
p
Pressure head
h
t
Total head
i
Hydraulic gradient
k
Permeability
K
0
At‐rest earth pressure coefficient
K
a
Active earth pressure coefficient
K
p
Passive earth pressure coefficient
LL
Liquid limit
M
s
Mass of solids
M
t
Total mass
M
w
Mass of water
n
Porosity
n
d
Number of total head drops in flow net
n
f
Number of flow channels in flow net
OCR
Overconsolidation ratio
p
a
Active pressure
p
p
Passive pressure
P
p
Preconsolidation pressure
PI
Plasticity index
PL
Plastic limit
φ
Total stress friction angle
φ′
Effective stress friction angle
ρ
Density
ρ
d
Dry density
ρ
m
Moist density
ρ
s
Density of solids
ρ
sat
Saturated density
ρ
t
Total density
ρ
w
Density of water
q
Seepage flow rate
R
a
Active earth pressure resultant
R
p
Passive earth pressure resultant
s
Settlement (
Chapter 4
) or Shear strength (
Chapter 5
)
s
u
Undrained shear strength
S
Degree of saturation
σ
Total normal stress
σ
1
Major principal total stress
σ
3
Minor principal total stress
σ
d
Deviator stress
σ
h
Horizontal total stress
σ
v
Vertical total stress
σ′
Effective normal stress
σ
1
′
Major principal effective stress
σ
3
′
Minor principal effective stress
σ
h
′
Horizontal effective stress
σ
v
′
Vertical effective stress
t
99
Time required for average degree of consolidation of 99%
T
Time factor
τ
Shear stress
u
Pore water pressure
u
σ
Stress‐induced pore water pressure
U
Average degree of consolidation
v
Discharge velocity
v
s
Seepage velocity
V
Volume
V
a
Volume of air
V
s
Volume of solids
V
t
Total volume
V
v
Volume of voids
V
w
Volume of water
w
Water content
Acknowledgments
Thank you, Caitlin Jacobson, Tony Robinson, and Michael Navin, for your thoughtful review comments, which improved this book.
Thank you, especially, Natalie Ehrlich for working closely with me to enhance the readability of the book. Also, thank you for the great idea to write the last chapter on site investigations, including the example that reinforces subjects learned in previous chapters.
Jeremy Britton
Portland, Oregon
About the Companion Website
This book is accompanied by a companion website:
www.wiley.com/go/EssentialsofSoilMechanics1e
This website includes:
Spreadsheet activities
Quick reference for Mohr–Coulomb failure lines
References for further learning
Introduction
Dear readers,
This is a short book about the basics of soil mechanics. Perhaps you are taking a soil mechanics course in a college civil engineering program. Maybe you are a practicing civil engineer, even a geotechnical engineer, who wants a refresher on the fundamentals. You could even be an instructor looking for support in teaching the sometimes challenging yet crucial aspects of soil mechanics. This short book is for you.
Seven concise chapters are used to introduce the topics of soil composition, stresses in the ground, seepage, consolidation, shear strength, active and passive pressures, and site investigations. The book is designed to be short enough to read over the weekend yet rich enough in content to serve as a longtime reference. The chapters in the book are previewed below.
This book is not intended to replace your textbook. Introductory soil mechanics and geotechnical engineering textbooks cover a broad curriculum. We do not cover everything you need to know here. This book is tailored to focus on the essential concepts that engineers need to know and to reinforce understanding in areas where students tend to struggle. The goal is to supplement your textbook with a friendly companion.
I took “Soil Engineering” in 1995. The textbook we used was Principles of Geotechnical Engineering, 3rd Edition, by Braja Das (1994). The textbook I have recently used for teaching soil mechanics is An Introduction to Geotechnical Engineering, 2nd Edition, by Robert Holtz, William Kovacs, and Thomas Sheahan (2010). I will refer you to these textbooks a few times to see how to do particular things that are important but do not need to be covered in this book on the basics. I am referring to these two introductory textbooks because I have them (as well as many other great books about geotechnical engineering, some of which I also refer to). It is very likely that if you have a different introductory textbook, your textbook also shows how to do these particular things.
Preview of Chapters
Chapter 1 is about soil composition, primarily the solid, water, and air phases. We talk about phase diagrams and the properties used to quantify a soil's phase relationships. We will see the importance of the volume of the voids and the amount of water in soils throughout the book. We demonstrate the use of phase relationships in the context of soil compaction. After this, we discuss the division of soils into the broad categories of coarse‐grained (sands and gravels) and fine‐grained (silts and clays). We discuss grain size distributions for coarse‐grained soils and Atterberg limits and fabric for fine‐grained soils. We end the chapter with a brief introduction to the Unified Soil Classification System.
Chapter 2 is all about stresses in the ground and how to evaluate them. We discuss the three important normal stresses: total stress, pore water pressure, and effective stress. We explain what effective stress is. We show how to calculate the vertical total stress, pore water pressure (for the hydrostatic condition), vertical effective stress, horizontal effective stress, and horizontal total stress in the ground. We then show how to construct and use Mohr circles to find normal and shear stresses on planes at any orientation. We end by discussing the estimation of stresses in the ground due to surface loads using the simple 2:1 method and elastic solutions. It is crucial to have a firm grasp on how to evaluate stresses in the ground before taking on the subjects of seepage, consolidation, shear strength, and active and passive pressures.
Chapter 3 is about seepage, the movement of water within the pores of soils. We begin by comparing the regimes of total head (elevation head plus pressure head) in a hydrostatic condition with no flow and in a seepage condition in which a gradient in total head drives flow. We learn about flow nets and how to use them to determine seepage‐related pore water pressures, hydraulic gradients, and the flow rate in seepage problems. We discuss Darcy's law and the coefficient of permeability of soil. Permeability is an important factor in a soil's consolidation and shear strength behavior.
Chapter 4 covers consolidation, which is the decrease in the volume of soil as pore water is squeezed out after loading. The related inverse phenomenon is rebound, which is the increase in volume that occurs after the load is removed. We describe how in a saturated, compressible soil, the pore water pressure feels the increase in stress from a new load first. Then, over time, the stress is transferred to the soil's effective stress as pore water seeps out. We show how to calculate the magnitude and time rate of consolidation settlement. We learn about the importance of a soil's stress history on its consolidation behavior. A soil's stress history is characterized by its preconsolidation pressure (the highest effective stress the soil has ever felt) or overconsolidation ratio (preconsolidation pressure divided by current vertical effective stress). In Chapter 5, we will see how a soil's shear strength is also affected by its stress history.
The main objective of Chapter 5 is to understand the shear strength of soils in both drained and undrained loading conditions. We use an example problem involving an embankment constructed over a sand foundation in one scenario and a clay foundation in another scenario. With a focus on the response of saturated soils to change‐in‐total‐stress loading conditions, we discuss the characteristics of drained behavior and undrained behavior. In drained loading, there is no buildup of stress‐induced pore water pressures since the load is applied slowly compared to the drainage conditions. Volume change occurs instead. In undrained loading, there is no volume change since the load is applied rapidly compared to the drainage conditions. Stress‐induced pore water pressures develop instead. We describe the Mohr–Coulomb failure line relationship between shear strength and effective stress. While shear strength always depends on the effective stress during loading, we do not usually know the effective stress during undrained loading. We describe how we relate undrained shear strength to the effective stress conditions (vertical effective stress and stress history) in the soil prior to the loading. At the end of the chapter, we discuss the common drained condition associated with a change in groundwater level, and we briefly discuss the shear strength of partially saturated soils.
Chapter 6 is about an important application of shear strength: active and passive pressures. These lateral earth pressures develop when a structure of some kind moves away from or into the soil. The soil mobilizes its shear strength, which leads to a decrease in earth pressure on the structure moving away from the soil and an increase in earth pressure on the structure moving into the soil. We learn how to determine active and passive pressures using Rankine's method. We also discuss the idea behind Coulomb's method and the generalization of his method for the analysis of complex scenarios. Finally, we talk about the amounts of movement required for soil to develop active and passive pressures.
In Chapter 7, the final chapter, we discuss a general approach to site investigations. We organize the steps into (1) understanding what is planned for the site, (2) looking for existing information about the site, (3) visiting the site, (4) developing a model and identifying data gaps, and (5) developing a subsurface exploration program. We imagine developing a subsurface exploration and testing program to support the design and construction of new features at a wildlife rehabilitation center close to a river. Along the way, we review some of the subjects from the previous chapters in the book involving soil composition, stresses in the ground, seepage, consolidation, and shear strength.
Chapters 1–6
