Question

Both falling head and constant head permeability tests are common experiments to obtain soil sample hydraulic conductivity.

Please provide 3 recommendations for each experiment to improve their accuracy of test results.

Answer 1

CONSTANT HEAD PERMEABILITY TEST :-

1 Waterused for testing is de-aired water at constant temperature.

2 The ratio of the cell diameter to the largest grain size diameter should be higher than 12.

3 During the test, the amount of water flowing through the soil column should be properly measured for given time intervals.

FALLING HEAD PERMEABILITY TEST :-

1 Before starting the flow measurements, the soil sample is saturated and the standpipes are filled with de-aired water to a given level.

2 The time required for the water in the standpipe to drop from the upper to the lower level should recorderd precisely.

3 The recorded time should be the same for each test within an allowable variation of about 10%