Civil Engineering Reference
In-Depth Information
Overflow
Water
Time, t
Filters
h
Soil
l
Q
Fig. 2.3
The constant head permeameter.
Hence k can be found from the expression
q
Ai
Ql
tAh
k
=
or
k
=
A series of readings can be obtained from each test and an average value of k determined. The test is
suitable for gravels and sand and could be used for many fill materials.
Example 2.1:
Constant head permeameter
In a constant head permeameter test the following results were obtained:
Duration of test
=
4.0 min
Quantity of water collected
=
300 ml
Head difference in manometer
=
50 mm
Distance between manometer tappings
=
100 mm
Diameter of test sample
=
100 mm
Determine the coefficient of permeability in m/s.
Solution:
π
100
4
×
2
300
4 60
A
=
=
7850
mm q
2
=
=
1 25
.
ml s
/
×
ql
Ah
1250 100
7850 50
×
×
k
=
=
=
3 18 10
.
×
−
1
mm s
/
=
3 2 10
.
×
−
4
m s
/
