Permeability tests are conducted
to estimate the coefficient of permeability (k). This will be used in pumping and
dewatering design.
Constant Head
Permeability Test
The soil sample is placed in a cylinder and
supported by a coarse filter or a wire mesh. The volume of water flowing through the
specimen under a constant total head is measured per unit time. This can later be related,
through calculations, to permeability.
Falling Head
Permeability Test
This method is more appropriate for fine-grained
soils. A coarse filter is placed above and below the sample and a standpipe is connected
to the top of the cylinder. Water drains into a constant head reservoir at the bottom, the
falling water level in the standpipe is measured at time intervals. This is later related,
through calculations, to permeability. |