ABSTRACT

Soil permeability, or the ability of a soil to transmit a fluid, is not only a function of the size and pattern of the individual particles, but also, and more importantly, the actual stratification which can cause the flow properties to depend upon direction (permeability anisotropy). It is difficult to obtain suitable specimens from the field for the purposes of permeability assessment, and so measurements are usually determined in situ. This is done by applying a head difference between the water in a borehole or piezometer and that in the surrounding ground. The flow resulting from this difference in hydraulic pressure is measured and expressed as a permeability - or, more accurately, a hydraulic conductivity - value.