Geology Reference
In-Depth Information
M
T0
M
d
(20-5)
S
0
H
s
)
100
A
r
w
(
H
0
107.98
75.94
(31.68) (1) (
1.981
S
0
0.881)
100
91.9%
At end of test:
M
Tf
M
d
M
d
(20-6)
w
f
100
M
T
f
234.54
127.17
107.37 g
M
d
203.11
127.17
75.94 g
107.37
75.94
75.94
w
f
100
41.4%
Initial void ratio:
e
0
H
0
H
s
(20-7)
H
s
1.981
0.881
0.881
e
0
1.249
[B] Time versus Deformation
As indicated previously, a graph of time along the abscissa on a logarith-
mic scale versus deformation dial readings along the ordinate on an
arithmetic scale is essential in order to evaluate the results of a consol-
idation test. The required graph for the given time-versus-deformation
data is presented in Figure 20-4. It must be emphasized again that the
curve of the dial readings versus the logarithm of time shown in the fig-
ure is for a loading increment from
0
to
500 lb/ft
2
. It would be necessary
to have additional such curves for a number of larger loading incre-
ments; however, these are not shown.
Following the procedure described in the section “Calculations,”
and referring to Figure 20-4 for a pressure of
500 lb/ft
2
, one can observe
that the deformations representing 100% and 0% primary consolida-
tions are 0.0158 in. and 0.0058 in., respectively. The deformation corre-
sponding to 50% consolidation is the average of 0.0158 and 0.0058,
or 0.0108 in.; and the time required for 50% consolidation (
t
50
) can be
determined from the figure to be 8.2 min.
[C] Void Ratio e
The change in thickness of the specimen,
H
, during the
500 lb/ft
2
loading can be computed by subtracting the initial dial reading (
0
) from
the reading representing 100% primary consolidation of the loading
(0.0158). Hence, the change in thickness (
Δ
H
) is 0.0158 in., or 0.0401 cm.
Δ
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