Civil Engineering Reference
In-Depth Information
Figure 15.9
Solutions for one-dimensional consolidation.
find the final settlement
ρ
∞
and, hence, the degree of consolidation at any time, and
thus plot
U
t
against time
t
. If the experimental
U
t
against
t
curve can be fitted to a
theoretical
U
t
against
T
v
curve, a relationship between
t
and
T
v
may be obtained and
c
v
found from Eq. (15.25). Two alternative curve-fitting approximations are available.
(a) A
√
(time) method
This method makes use of the observation that settlement against
√
(time) curves have
an initial portion that may be approximated by a straight line, and this straight line
can be fitted to Eq. (15.34). Figure 15.10(a) shows the results of a single s
ta
ge of con-
solidation of a sample of clay in an oedometer test plot
te
d as
U
t
against
√
t
. The slope
of the initially linear part of the curve is given by
√
t
1
, as shown in Fig. 15.10(a).
The experimental curve and the curve in Fig. 15.10(a) fit when
U
t
=
1 and
t
=
t
1
in
Eq. (15.25). Hence,
C
v
t
1
H
2
√
3
2
T
v
=
=
(15.35)
3
H
2
4
t
1
c
v
=
(15.36)
Figure 15.10
Determination of
c
v
from oedometer test results by curve fitting.
