The measurement of the hydraulic permeability of saturated soil in situ I. Principles of a proposed method

Abstract

A steady-state method is described for measuring the permeability of soil in situ ; it is applicable only to saturated soil below the water table. A pair of small wells, in one of which is placed a pump, forms a water circulating system. The pump depresses the level in one well and the pumped water, being passed through a flowmeter and emptied back into the second well, maintains a level in the latter higher than the static equilibrium level. The difference of levels in the wells is related to the rate of flow of water and to the soil permeability. In anisotropic media the method gives apparent horizontal permeability. The use of two pairs of wells, the planes containing the axes of each pair being suitably oriented, enables us to determine the permeabilities in the directions of the horizontal axes, of anisotropy. Combining our method with Kirkham’s, which provides an estimate of apparent permeability which is dependent upon both horizontal and vertical permeabilities, we are able to calculate the axial permeabilities of triaxially anisotropic material.