,Craig’s Soil Mechanics Seventh Edition Solutions
Manual
,
,Craig’s Soil Mechanics Seventh
Edition Solutions Manual
R.F. Craig
Formerly
Department of Civil Engineering University
of Dundee UK
,First published 1992
by E & FN Spon, an imprint of Thomson Professional Second
edition 1997
Third edition 2004
11 New Fetter Lane, London EC4P 4EE
Simultaneously published in the USA and Canada by
Spon Press
29 West 35th Street, New York, NY 10001
This edition published in the Taylor & Francis e-Library, 2004.
“To purchase your own copy of this or any of Taylor & Francis or Routledge’s
collection of thousands of eBooks please go to www.eBookstore.tandf.co.uk.”
Spon Press is an imprint of the Taylor & Francis Group
ª 1992, 1997, 2004R.F. Craig
All rights reserved. No part of this book may be reprinted or reproduced or utilised
in any form or by any electronic, mechanical, or other means, now known or
hereafter invented, including photocopying and recording, or in any information
storage or retrieval system, without permission in writing from the publishers.
British Library Cataloguing in Publication Data A
catalogue record for this book is available from
the British Library
Library of Congress Cataloging in Publication Data
A catalog record for this book has been requested
ISBN 0-203-31104-3 Master e-book ISBN
ISBN 0-203-67167-8 (Adobe eReader Format)
ISBN 0–415–33294–X (Print edition)
,Contents
1 Basic characteristics of soils 1
2 Seepage 6
3 Effective stress 14
4 Shear strength 22
5 Stresses and displacements 28
6 Lateral earth pressure 34
7 Consolidation theory 50
8 Bearing capacity 60
9 Stability of slopes 74
,Author’s note
In order not to short-circuit the learning
process it is vital that the reader should
attempt the problems before referring to the
solutions in this manual.
,Chapter 1
Basic characteristics of soils
1.1
Soil E consists of 98% coarse material (31% gravel size; 67% sand size) and 2% fines.
It is classified as SW: well-graded gravelly SAND or, in greater detail, well-graded
slightly silty very gravelly SAND.
Soil F consists of 63% coarse material (2% gravel size; 61% sand size) and 37%
non-plastic fines (i.e. between 35 and 65% fines); therefore, the soil is classified as MS:
sandy SILT.
Soil G consists of 73% fine material (i.e. between 65 and 100% fines) and 27% sand
size. The liquid limit is 32 and the plasticityindex is 8 (i.e. 32— 24), plotting marginally
below the A-line in the ML zone on the plasticity chart. Thus the classification is ML:
SILT (M-SOIL) of low plasticity. (The plasticity chart is given in Figure 1.7.)
Figure Q1.1
,2 Basic characteristics of soils
Soil H consists of 99% fine material (58% claysize; 47% silt size). The liquid limit is
78 and the plasticity index is 47 (i.e. 78— 31), plotting above the A-line in the CV zone
on the plasticity chart. Thus the classification is CV: CLAY of very high plasticity.
1.2
From Equation 1.17
1.00
1 + e = G (1 + w ρw 2.70 × 1.095 × = 1.55
s ) = 1.91
ρ
; e = 0.55
Using Equation 1.13
wGs 0.095 × 2.70
Sr = = = 0.466 (46.6%)
e 0.55
Using Equation 1.19
G +e 3.25
ρsat = s
3
ρw = × 1.00 = 2.10 Mg/m
1 +e 1.55
From Equation 1.14
e 0.55
w = = = 0.204 (20.4%)
Gs 2.70
1.3
Equations similar to 1.17–1.20 apply in the case of unit weights; thus,
Gs 2.72 3
цd = цw = × 9.8 = 15.7 kN/m
1+e 1.70
Gs + e 3.42
цsat =
3
цw = × 9.8 = 19.7 kN/m
1 +e 1.70
Using Equation 1.21
Gs — 1 1.72 3
ц' = ц
1 + e w = 1.70 × 9.8 = 9.9 kN/m
Using Equation 1.18a with Sr = 0.75
Gs + Sre 3.245 3
ц= цw = × 9.8 = 18.7 kN/m
1 +e 1.70
, Basic characteristics of soils 3
Using Equation 1.13
Sre 0.75 × 0.70
w= = = 0.193 (19.3%)
Gs 2.72
The reader should not attempt to memorize the above equations. Figure 1.10(b)
should be drawn and, from a knowledge of the definitions, relevant expressions can
be written by inspection.
1.4
r
Volume of specimen = ×382 ×76 = 86 200 mm3
4
Mass 168.0
Bulk density (ρ)= = = 1.95 Mg/m 3
Volume 86 200 × 10—3
168.0 — 130.5
Water content (w = 0.287 (28.7%)
)= 130.5
From Equation 1.17
ρw 1.00
2.73 × 1.287 × = 1.80
1 + e = Gs(1 + w ) =
ρ 1.95
; e = 0.80
Using Equation 1.13
wGs 0.287 × 2.73
Sr= = = 0.98 (98%)
e 0.80
1.5
Using Equation 1.24
ρ 2.15 3
ρd = = = 1.92 Mg/m
1 +w 1.12
From Equation 1.17
ρw 1.00
1 + e = Gs(1 + w ) = 2.65 × 1.12 × = 1.38
ρ 2.15
; e = 0.38
Using Equation 1.13
wGs 0.12 × 2.65
Sr = = = 0.837 (83.7%)
e 0.38
Manual
,
,Craig’s Soil Mechanics Seventh
Edition Solutions Manual
R.F. Craig
Formerly
Department of Civil Engineering University
of Dundee UK
,First published 1992
by E & FN Spon, an imprint of Thomson Professional Second
edition 1997
Third edition 2004
11 New Fetter Lane, London EC4P 4EE
Simultaneously published in the USA and Canada by
Spon Press
29 West 35th Street, New York, NY 10001
This edition published in the Taylor & Francis e-Library, 2004.
“To purchase your own copy of this or any of Taylor & Francis or Routledge’s
collection of thousands of eBooks please go to www.eBookstore.tandf.co.uk.”
Spon Press is an imprint of the Taylor & Francis Group
ª 1992, 1997, 2004R.F. Craig
All rights reserved. No part of this book may be reprinted or reproduced or utilised
in any form or by any electronic, mechanical, or other means, now known or
hereafter invented, including photocopying and recording, or in any information
storage or retrieval system, without permission in writing from the publishers.
British Library Cataloguing in Publication Data A
catalogue record for this book is available from
the British Library
Library of Congress Cataloging in Publication Data
A catalog record for this book has been requested
ISBN 0-203-31104-3 Master e-book ISBN
ISBN 0-203-67167-8 (Adobe eReader Format)
ISBN 0–415–33294–X (Print edition)
,Contents
1 Basic characteristics of soils 1
2 Seepage 6
3 Effective stress 14
4 Shear strength 22
5 Stresses and displacements 28
6 Lateral earth pressure 34
7 Consolidation theory 50
8 Bearing capacity 60
9 Stability of slopes 74
,Author’s note
In order not to short-circuit the learning
process it is vital that the reader should
attempt the problems before referring to the
solutions in this manual.
,Chapter 1
Basic characteristics of soils
1.1
Soil E consists of 98% coarse material (31% gravel size; 67% sand size) and 2% fines.
It is classified as SW: well-graded gravelly SAND or, in greater detail, well-graded
slightly silty very gravelly SAND.
Soil F consists of 63% coarse material (2% gravel size; 61% sand size) and 37%
non-plastic fines (i.e. between 35 and 65% fines); therefore, the soil is classified as MS:
sandy SILT.
Soil G consists of 73% fine material (i.e. between 65 and 100% fines) and 27% sand
size. The liquid limit is 32 and the plasticityindex is 8 (i.e. 32— 24), plotting marginally
below the A-line in the ML zone on the plasticity chart. Thus the classification is ML:
SILT (M-SOIL) of low plasticity. (The plasticity chart is given in Figure 1.7.)
Figure Q1.1
,2 Basic characteristics of soils
Soil H consists of 99% fine material (58% claysize; 47% silt size). The liquid limit is
78 and the plasticity index is 47 (i.e. 78— 31), plotting above the A-line in the CV zone
on the plasticity chart. Thus the classification is CV: CLAY of very high plasticity.
1.2
From Equation 1.17
1.00
1 + e = G (1 + w ρw 2.70 × 1.095 × = 1.55
s ) = 1.91
ρ
; e = 0.55
Using Equation 1.13
wGs 0.095 × 2.70
Sr = = = 0.466 (46.6%)
e 0.55
Using Equation 1.19
G +e 3.25
ρsat = s
3
ρw = × 1.00 = 2.10 Mg/m
1 +e 1.55
From Equation 1.14
e 0.55
w = = = 0.204 (20.4%)
Gs 2.70
1.3
Equations similar to 1.17–1.20 apply in the case of unit weights; thus,
Gs 2.72 3
цd = цw = × 9.8 = 15.7 kN/m
1+e 1.70
Gs + e 3.42
цsat =
3
цw = × 9.8 = 19.7 kN/m
1 +e 1.70
Using Equation 1.21
Gs — 1 1.72 3
ц' = ц
1 + e w = 1.70 × 9.8 = 9.9 kN/m
Using Equation 1.18a with Sr = 0.75
Gs + Sre 3.245 3
ц= цw = × 9.8 = 18.7 kN/m
1 +e 1.70
, Basic characteristics of soils 3
Using Equation 1.13
Sre 0.75 × 0.70
w= = = 0.193 (19.3%)
Gs 2.72
The reader should not attempt to memorize the above equations. Figure 1.10(b)
should be drawn and, from a knowledge of the definitions, relevant expressions can
be written by inspection.
1.4
r
Volume of specimen = ×382 ×76 = 86 200 mm3
4
Mass 168.0
Bulk density (ρ)= = = 1.95 Mg/m 3
Volume 86 200 × 10—3
168.0 — 130.5
Water content (w = 0.287 (28.7%)
)= 130.5
From Equation 1.17
ρw 1.00
2.73 × 1.287 × = 1.80
1 + e = Gs(1 + w ) =
ρ 1.95
; e = 0.80
Using Equation 1.13
wGs 0.287 × 2.73
Sr= = = 0.98 (98%)
e 0.80
1.5
Using Equation 1.24
ρ 2.15 3
ρd = = = 1.92 Mg/m
1 +w 1.12
From Equation 1.17
ρw 1.00
1 + e = Gs(1 + w ) = 2.65 × 1.12 × = 1.38
ρ 2.15
; e = 0.38
Using Equation 1.13
wGs 0.12 × 2.65
Sr = = = 0.837 (83.7%)
e 0.38
