Geoscience Reference
In-Depth Information
. The effective stress
'
is just the difference of total stress and the actual pore
pressure.
total stress
total stress
total stress
total stress
total stress
total stress
u
u
u
u
u
u
'
'
'
'
'
'
pore pressure
pore pressure
pore pressure
pore pressure
pore pressure
pore pressure
0.35
0.35
0.35
0.35
0.35
0.35
4.65 kPa
4.65 kPa
4.65 kPa
4.65 kPa
4.65 kPa
4.65 kPa
2.5
2.5
2.5
2.5
2.5
2.5
(a) permeability test (b) stress field
Figure 4.14 Permeability test interpretation
phreatic surface
phreatic surface
phreatic surface
phreatic surface
s
s
s
s
H
1
H
1
H
1
H
1
phreatic surface
phreatic surface
phreatic surface
phreatic surface
Q
Q
Q
Q
H
1
H
1
H
1
H
1
Q
Q
Q
Q
s
s
s
s
H
2
HH
2
H
2
HH
2
H
2
H
2
H
2
H
2
scale
10 cm
scale
10 cm
L
L
L
L
10 cm
10 cm
10 cm
10 cm
L
L
L
L
Figure 4.15 Hele Shaw box tests
application 4.8
Two tests are performed with the Hele Shaw model (Fig 4.15). The formula of
Dupuit can be assigned to the area indicated (dashed box). Sketch a graph of the
effect of relative discharge (
Q
test
2
/
Q
test
1
) versus relative opening (
s
test
2
/
s
test
1
) by
determining three points (two are obvious, and one is to be determined by the two
tests). What does this result tell you about a leak in a wall?
Search WWH ::
Custom Search