Estimating hydraulic conductivity from piezocone soundings

A method for estimating the hydraulic conductivity of soils from piezocone penetration tests is suggested in this paper. By invoking Darcy's law over the finite time required for an increment of cone penetration, it is argued that there will be some water movement through the soil around the cone, albeit very small if the soil is very fine grained. Based on this argument, and noting the comprehensive test data collected previously by Elsworth & Lee, a bi-linear relation between the dimensionless piezocone sounding metric B_qQ_t and the dimensionless hydraulic conductivity index K_D plotted on double logarithmic scales has been proposed for soils ranging from sands to clays. It is demonstrated that these revised relationships can be used to evaluate plausible values of hydraulic conductivity from piezocone sounding records taken at two different clay soil sites in Saga and Yokohama, Japan. The major significance of this work is in extending the range of application of the method first proposed by Elsworth & Lee for sands to almost all soil types. This was possible after appropriate modification of Elsworth and Lee's original method.