The colour was a mix of yellow and light brown water

•
The colour was a mix of yellow and light brown.
•
Water expelled from the sample very easily when shaken or patted lightly.
•
After handling the soil sample, whitish and yellow powdery material was left on one’s hands.
•
Soil grains present were predominantly sand sized with a small amount of fine particles present
(approx 10 %).
•
A simple dynamic cone penetrometer test was performed and revealed the soil had a relative
density of 35 %.
Properly describe each layer of soil as best you can (based on the information provided) in accordance
with AS1726-1993: Geotechnical Site Investigations Code.

CVE20004 - Geomechanics
R. P. Evans Page No. 6.7 of 6.21
6.1.3 Soil Hydraulics
Q3.1 A coarse sand sample (120 mm long and 73 mm in diameter) was tested in a constant head
permeameter. The total head loss across the sample was 1000 mm. The quantity of water discharged
was 5000 ml in 72 seconds. Determine the coefficient of permeability for the sand sample in cm/sec.
Q3.2. A constant head permeability test was performed on a soil sample 73 mm in diameter and 140 mm long
with a measured discharge of 1.00 x 10
-5
m
3
/min. If the total head loss was 1.0m and the soil was shown
to have a dry mass of 985 grams with the specific gravity of the soil particles 2.7, determine:
(a) the coefficient of permeability in m/sec,
(b) the average velocity or superficial velocity, and
(c) the seepage or void velocity.
Q3.3 A falling head permeability test was performed on a soil sample 73 mm in diameter and 180 mm long.
The diameter of the standpipe was 10mm. Over 3 hours and 13 minutes, the water level in the standpipe
dropped from a height of 650 mm (above a constant water level) to 500 mm. Determine the coefficient of
permeability for the soil sample.
Q3.4 What would the water level in Q3.3 drop to if the experiment was allowed to continue for 4 more hours.
Q3.5 A layer of sand overlies a horizontal stratum of rock. A field pump test was carried out to determine the
permeability of the soil via a well that was driven through to the bottom of the sand layer. Water was then
pumped from this test well until the water level stabilised at a flow rate of 3 x 10
-3
m
3
/sec. For this
equilibrium flow condition, the water level in two adjacent observation wells was recorded and shown
below:
Observation
Well No.
Distance from
Test Well
Height of water table above
Impermeable Layer
1 12.5m 4.25m
2 25m 6.5m
Find the coefficient of permeability of the sand.
Q3.6 A 106 mm diameter perforated casing was installed into a sandy stratum to a depth of 13 m below the
water table, resting on an impervious mudstone layer. Two observation wells were installed at 20m and
40m distance from the test well. Water was pumped out of the main borehole until steady state pumping
of 200 litres per minute was achieved. The water level in the two observation wells dropped by 1.45 and
1.25m respectively. Estimate the coefficient of permeability of the sandy stratum.