Civil Engineering Reference
In-Depth Information
Table 8.1
Results of isotropic compression tests - Example 8.1
Mean effective stress p
(kPa)
In p
(kPa)
Specific volume v
20
3.00
2.65
60
4.09
2.43
200
5.30
2.19
1000
6.91
1.87
200
5.30
1.95
60
4.09
2.01
Figure 8.13
Isotropic compression and swelling - Example 8.1.
2.22. The bulk modulus
K
N
=
3.25 and
v
κ
=
is not a constant: from Eq. (8.1), for
the second and last increments between
p
=
60 kPa and
p
=
200 kPa.
p
ε
K
=
200
−
60
v
=
2.43)/2.43
=
1.42MPa
−
(2.19
−
p
ε
K
=
60
−
200
v
=
1.95)/1.95
=
4.55MPa
−
(2.01
−
Example 8.2: Determination of soil behaviour during isotropic compression
A soil has
the parameters
3.25. A sample is subjected to the
sequence of isotropic loading and unloading given in the second column in Table 8.2.
At each stage the overconsolidation ratio
R
p
is given by Eq. (8.6). For the normally
consolidated state (
R
p
λ
=
0.20,
κ
=
0.05 and
N
=
1) the specific volume is given by Eq. (8.2). At the point C,
the specific volume is given by both Eqs. (8.2) and (8.3) and hence
=
)ln
p
=
v
κ
=
N
−
(
λ
−
κ
3.25
−
(0.20
−
0.05) ln 600
=
2.29
For the overconsolidated states the specific volume is given by Eq. (8.3).
