SOLUTIONS MANUAL
For
Principles of
Geotechnical
Engineering
Ninth Edition
BRAJA M. DAS
KHALED SOBHAN
, Contents
Chapter 2............................................................................................................................. 1
Chapter 3........................................................................................................................... 15
Chapter 4........................................................................................................................... 27
Chapter 5........................................................................................................................... 33
Chapter 6........................................................................................................................... 43
Chapter 7........................................................................................................................... 53
Chapter 8........................................................................................................................... 63
Chapter 9........................................................................................................................... 71
Chapter 10......................................................................................................................... 81
Chapter 11......................................................................................................................... 97
Chapter 12....................................................................................................................... 113
Chapter 13....................................................................................................................... 123
Chapter 14....................................................................................................................... 135
Chapter 15....................................................................................................................... 143
Chapter 16....................................................................................................................... 159
Chapter 17....................................................................................................................... 175
, Chapter 2
2
D60 0.48 D30 0.25 2
2.1 Cu = = = 4.36 ; Cc = = = 1.18
D10 0.11 ( D60 )( D10 ) ( 0.48)( 0.11)
Since Cu > 4 and Cc is between 1 and 3, the soil is well graded.
2
D60 1.1 D30 0.412
2.2 Cu = = = 6.11 ; Cc = = = 0.727 ≈ 0.73
D10 0.18 ( D60 )( D10 ) (1.1)( 0.18)
Although Cu > 6, Cc is not between 1 and 3. The soil is poorly graded.
2.3 The D10, D30, and D60 for soils A, B, and C are obtained from the grain-size
distribution curves.
2
D60 3.5 D30 1.95 2
Soil A: Cu = = = 17.5 ; Cc = = = 5.43
D10 0.2 ( D60 )( D10 ) (3.5)(0.2)
Although Cu > 6, Cc is not between 1 and 3. The sand is poorly graded.
1
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, 2
D60 1 .5 D30 0.75 2
Soil B: Cu = = = 8.82 ; Cc = = = 2.2
D10 0 .17 ( D60 )( D10 ) (1.5)(0.17)
Cu > 6 and Cc is between 1 and 3. The sand is well graded.
D60 0.55 D302 0.22 2
Soil C: Cu = = = 17.2; Cc = = = 2.75
D10 0.032 ( D60 )( D10 ) (0.55)(0.032)
Cu > 6 and Cc is between 1 and 3. The sand is well graded.
2.4 a.
Sieve Mass of soil retained Percent retained Percent
No. on each sieve (g) on each sieve finer
4 0.0 0.0 100.0
10 18.5 4.4 95.6
20 53.2 12.6 83.0
40 90.5 21.5 61.5
60 81.8 19.4 42.1
100 92.2 21.9 20.2
200 58.5 13.9 6.3
Pan 26.5 6.3 0
∑ 421.2 g
The grain-size distribution is shown in the figure.
b. D60 = 0.4 mm; D30 = 0.2 mm; D10 = 0.095 mm
2
© 2018 Cengage Learning®. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.