Permeability Test for Fine-Grained and Granular Soils (Falling-Head Method) - Soil Properties: Testing, Measurement, and Evaluation - page 275

A laboratory test was conducted according to the procedure described
previously. The following data were obtained:

NUMERICAL
EXAMPLE

Mass of permeameter (mold) with base plate and gasket attached

1,098.5 g
Mass of permeameter (mold) with base plate and gasket attached
plus soil 3,401.1 g

Length of specimen, L 15.80 cm

Diameter of specimen, D 10.16 cm

For water content determination:
Mass of air-dried soil plus can 308.17 g

Mass of oven-dried soil plus can 305.40 g

53.60 g
Cross-sectional area of standpipe (burette), a

Mass of can

1.83 cm 2

Hydraulic head at beginning of test, h 1 150.0 cm (same reading

for each of three trials)
Hydraulic head at end of test, h 2 20.0 cm (same reading for each

of three trials)
Total times for water in burette to drop from h 1 to h 2 , t 32.3 s,

32.6 s, 31.7 s (respective values for each of three trials)
Water temperature, T 22°C (same value for each of three trials)

Additionally, the specific gravity of the solids is known to be 2.71 from a
previous test.

[A] Unit Weight Determination

With the soil specimen's diameter known, its cross-sectional area A can
be calculated:

A p D 2
4

p ( 10.16 ) 2
4

81.07 cm 2

With the length of the soil specimen known, its volume can be computed:

Volume of specimen (81.07)( 15.80 ) 1,280.9 cm 3

With the mass of the permeameter and of the permeameter plus soil
known, the air-dried soil specimen's mass and then its unit weight can
be determined:

Mass of air-dried soil specimen 3,401.1 1,098.5 2,302.6 g

2,302.6
1,280.9

Unit weight of air-dried soil specimen 62.4

112.2 lb/ft 3
The water content of the air-dried soil sample can be determined as follows: