Constant Head apparatus

This method describes a procedure for the determination of the permeability of water through granular (cohesionless) soils in a steady-state condition. The procedure is to establish representative values of the coefficient of permeability, k, of granular soils that may occur in natural deposits as placed in embankments, or when used as base courses under pavements. The determination of k was developed under the assumptions of the validity of Darcy’s Law, which states that the coefficient of permeability is the ratio of the flow rate to the hydraulic gradient. In order to limit consolidation influences during testing, this procedure is limited to disturbed granular soils with permeability in range of 1 to 1x10^-5.