Civil Engineering Reference
In-Depth Information
where
Δ
z
=
the grid spacing, and also the increment of dam thickness placed in time
Δ
t
γ
=
unit weight of dam material
B
=
pore pressure coefficient
c
∆
∆
2
t
v
r
=
z
In order that
Δ
z is constant throughout the full height of the dam, all construction periods must be
approximated to the same linear relationship and then transformed into a series of steps. The formula
can only be applied to a layer that has some finite thickness, and as the layer does not exist initially it is
necessary to obtain a solution by some other method for the early stages of construction when the dam
is insufficiently thick for the formula to be applicable. Smith (
1968b)
has shown how a relaxation procedure
can be used for this initial stage.
Example 12.6:
Excess pore pressure distribution by numerical
method
At a stage in its construction an earth embankment has attained a height of 9.12 m and
has the excess pore water pressure distribution shown in Fig.
12.15a
. A proposal has
been made that further construction will be at the rate of 1.52 m thickness of materi
al
placed in one month, the unit weight of the placed material to be 19.2 kN/m
3
and its
B
Fig. 12.15
Example
12.6.
