Constant-head test

To analyse the permeability of coarse-grained soils the constant-head method is used; the larger particles have a fast hydraulic conductivity. This method is made for testing re-constituted and disturbed coarse-grained soils. The constant head device consists of a reservoir on top to hold de-aired water, a cell with the sample material (the permeameter), and a reservoir at the bottom to hold water that has permeated through. The soil sample is saturated before the test starts. During set time intervals the pressure and volume of the permeated water are measured, as well as the height and cross-sectional area of the sample. These parameters are then used to calculate the coefficient of permeability.