Infiltration and Saturated Hydraulic Conductivity of Compacted Clay

Abstract

Infiltration tests were conducted in the laboratory to study water movement during infiltration in compacted clay and to determine the suction head at the wetting front as defined in the Green-Ampt infiltration equation. Tests were conducted on two clays, having low and high plasticity indices. Results of the tests show that the wetting front is diffuse and becomes increasingly so as it penetrates deeper into the soil. The wetting front is also more diffuse for molding water contents near or wet of optimum water content and for clay with higher plasticity index. Suction head at the wetting front has been found to decrease as the wetting front penetrates into the soil, with the rate of dissipation depending on the molding water content and soil type. For the clay with low plasticity index, the initial suction head at the wetting front was largest and decreased the fastest when the molding water content was near optimum. For the clay with high plasticity index, similar initial suction head and rate of dissipation were measured at various molding water contents. Soil-specific equations are presented to estimate the suction head at the wetting front using the air-entry pressure.