TM 5-818-1 / AFM 88-3, Chap. 7
theory relates the degree of consolidation and time
H
=
length of the drainage path, which in
subsequent to loading according to the following
the case of a specimen or stratum
draining from top and bottom would be
half the thickness of the specimen or
U(%) = f(T)
(5-3)
stratum
t
=
time corresponding to U
with
t
(5-4)
T=
cv
2
The relation between time factor and percent
H
consolidation for various boundary conditions is shown in
figure 5-5. If the values of cv and H are known for a
where
stratum of clay with given boundary conditions, the
U=
degree of consolidation or ratio of
theoretical curve can be replotted in the form of a
settlement that has occurred at a given
percent consolidation-time curve; if the ultimate
time to the ultimate settlement
settlement of the layer has been computed, the curve
T
=
dimensionless number called the time
can be further modified into a settlement-time curve. In
factor that depends upon loading and
order to compute, cv, it is necessary to transform the
boundary conditions
laboratory time-consolidation curve for the load
=
property of the soil known as the
cv
increment in question into the theoretical curve. A
coefficient of consolidation
method for ad- justing the laboratory curve in order to
compute the
U. S. Army Corps of Engineers
Figure 5-5. Time factors for various boundary conditions.
5-9
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