Civil Engineering Reference
In-Depth Information
Table 4.1
Compression of saturated soils.
Soil type
Soft clay
Stiff clay
Compact silt
Loose sand
Dense sand
n (%)
60
37
35
46
43
C
c
(m
2
/kN)
4.79
×
10
−
4
3.35
×
10
−
5
9.58
×
10
−
5
2.87
×
10
−
5
1.44
×
10
−
5
B
0.9998
0.9982
0.9994
0.9973
0.9951
′
+
′
Change in volume of soil skeleton
,
∆
V
=−
C V (
∆
σ
2
∆
σ
)
c
c
1
3
i.e.
V
C
c
∆
V
=−
[(
∆
σ
−
∆
σ
)
−
3
∆
u
]
c
1
3
d
3
Now
V
C n u V and V must equal V
∆
=−
∆
∆
∆
v
v
d
c
v
1
3
⇒
C
(
∆
σ
−
∆
σ
)
−
C u
∆
=
C n u
∆
c
1
3
c
d
v
d
or
u C
(
nC
)
C
(
)
∆
+
=
∆
σ
−
∆
σ
d
c
v
c
1
3
1
1
3
⇒
∆
u
=
(
∆
σ
−
∆
σ
)
d
1
3
nC
C
1
v
c
+
1
3
B
(
σ
3
)
= ×
∆
σ
−
∆
1
Now
∆
u
=
∆
u
+
∆
u
a
d
1
3
(
⇒
∆
u B
=
∆
σ
+
∆
σ
−
∆
σ
)
3
1
3
Generally a soil is not perfectly elastic and the above expression must be written in the form:
∆
=
B
[
∆
σ
+
A
(
∆
σ
−
∆
σ
)]
u
3
1
3
where A is a coefficient determined experimentally.
The expression is often written in the form:
∆
=
B
∆
σ
+
A
(
∆
σ
−
∆
σ
)
where
A
=
AB
u
3
1
3
A
and B can be obtained directly from the undrained triaxial test. As has been shown, for a saturated soil
B
=
1.0 and the above expression must be.
∆
u
=
∆
σ
+
A
(
∆
σ
−
∆
σ
)
3
1
3
