Environmental Engineering Reference
In-Depth Information
t = 0 min
t = 2 min
t = 10.7 min
t = 25.3 min
t = 1440 min
t = 0.8 min
t = 120 min
250
Pore-water pressures
High air entry disk ports
Pore-air pressures
Bronze ports
210
170
130
90
50
Δ
u
a
10
Δ
u
w
-30
70
80
90
100
110
120
130
Pore pressures,
u
(kPa)
(a)
0
2
Water
Total
4
6
8
10
12
0
200
400
600
800
1000
1200
1400
1600
Elapsed time,
t
(min)
(b)
Figure 16.16
Pore pressures and volume changes during consolidation test on silty sand (No.
SIFG): (a) pore-air and pore-water pressure isochrones; (b) total and water volume changes (from
Rahardjo, 1990).
u
w
=
pore-water pressure at any time, and
defined as
2
d
d
=
length of drainage path (note: double drainage was
assumed).
u
a
dy
0
U
a
=
1
−
(16.45)
2
d
u
a
0
dy
The time factor for the water phase is defined as
0
c
v
t
d
2
and
c
v
t
d
2
T
w
=
(16.44)
T
a
=
(16.46)
where:
where:
U
a
=
average degree of consolidation with respect to the
air phase,
t
=
elapsed time.
T
a
=
time factor with respect to the air phase,
Similarly, the average degree of consolidation and the
dimensionless time factor with respect to the air phase are
u
a
0
=
initial pore-air pressure, and
u
a
=
pore-air pressure at any time.
Search WWH ::
Custom Search