Volume 35, Issue 1 (January 2012)
Validation of a Centrifuge Permeameter for Investigation of Transient Infiltration and Drainage Flow Processes in Unsaturated Soils
This paper focuses on the validation of a centrifuge permeameter and testing methodology developed to investigate transient water flow processes in unsaturated soils. The centrifuge permeameter is capable of controlling the boundary conditions for infiltration and drainage and contains instrumentation to measure profiles of the volumetric water content and matric suction with height in a soil layer during centrifugation. Evaluations of the measured matric suction and volumetric water content profiles from a series of infiltration and drainage tests performed on a fine sand at centrifuge acceleration levels ranging from 20 to 50 times earth gravity indicate that the established equations for calculating the hydraulic conductivity of unsaturated soil at steady-state conditions might not be appropriate, except at higher centrifuge accelerations. The transient profiles were also analyzed using a form of the instantaneous profile method in which the centrifuge acceleration was incorporated into the hydraulic gradient. Although the calculated soil water retention curve and hydraulic conductivity function data show some scatter, the hysteretic behavior of the soil during wetting and drying could be assessed.