Chapter 4 Plasticity and Structure of Soil

Chapter 4

4.1 a. Refer to the plot
of w versus N.
LL = 29.0


b. PI = LL – PL
= 29.0 – 13.4
= 15.6




w − PL 32 − 13.4
4.2 LI = = = 1.19
LL − PL 15.6




4.3 a. From the plot,
LL = 23.6.


b. PI = LL – PL
= 23.6 – 19.1
= 4.5




19
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

, w − PL 21 − 19.1
4.4 LI = = = 0.422
LL − PL 4.5


⎛ M − M2 ⎞ ⎛V −Vf ⎞
4.5 SL = ⎜⎜ 1 ⎟⎟(100) − ⎜⎜ i ⎟⎟( ρ w )(100)
⎝ M2 ⎠ ⎝ M2 ⎠


⎛ 34 − 24 ⎞ ⎛ 20.2 − 14.3 ⎞
=⎜ ⎟(100) − ⎜ ⎟(1)(100) = 17.08
⎝ 24 ⎠ ⎝ 24 ⎠


M2 24
SR = = = 1.68
Vf ρ w (14.3)(1)



⎛ M − M2 ⎞ ⎛V −Vf ⎞
4.6 SL = ⎜⎜ 1 ⎟⎟(100) − ⎜⎜ i ⎟⎟( ρ w )(100)
⎝ M2 ⎠ ⎝ M2 ⎠


⎛ 44.6 − 32.8 ⎞ ⎛ 16.2 − 10.8 ⎞
=⎜ ⎟(100) − ⎜ ⎟(1)(100) = 19.51
⎝ 32.8 ⎠ ⎝ 32.8 ⎠

M2 32.8
SR = = = 3.03
Vf ρw (10.8)(1)




CRITICAL THINKING PROBLEMS



PI
4.C.1 a. From Eq. (4.26): A =
(% of clay - size fraction, by weight)

The computed PI values are provided in the table on the following page.




20
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.