Civil Engineering Reference
In-Depth Information
Figure 13.1
Compression of lightly and heavily overconsolidated soils.
overconsolidated, the state does not reach the state boundary surface and in Cam clay
the strains are taken to be elastic throughout the loading path C
D. The stress-strain
curves are shown in Fig. 13.1(b) and these correspond to the volume changes shown
in Fig. 13.1(c).
For lightly overconsolidated soils following the path A
→
→
B in Fig. 13.1, the greater
proportion of the strains occur along Y
B as the state moves on the state boundary
surface and only a small proportion occurs along A
→
Y, where the soil is inside
the boundary surface. For these soils we can use the Cam clay or similar theories to
calculate ground movements since the significant errors which occur in the calculations
of the elastic strains along A
→
→
Y will be relatively small compared with the total
strains for the whole path A
B. For heavily overconsolidated soils, on the other
hand, the state remains inside the state boundary surface for the whole path C
→
D
and the errors in the strains calculated using the Cam clay theories will be relatively
large.
→
13.3 Stiffness-strain relationships for soil
From Eqs. (3.21) to (3.25) a general set of constitutive equations can be written as
δ
3
G
δε
q
J
s
=
(13.1)
p
J
K
δ
δε
v
