Unsaturated Soil Hydraulic Parameter Studies

摘要

Different field and laboratory methods for determining the hydraulic properties of unsaturated soils were studied. Drying moisture retention curves were measured on undisturbed soil samples with a pressure plate apparatus, and wetting soil moisture retention curves were measured on repacked soil columns via a capillary rise experiment Saturated hydraulic conductivities were measured in-situ with a Guelph permeameter, and in the laboratory with falling head tests. Finally, an inverse modeling technique was used to analyze transient flow data from in-situ cone permeameter and laboratory multi-step outflow experiments to simultaneously obtain wetting and drying curves for both the moisture retention and the hydraulic conductivity functions. The retention curves obtained from analysis of the cone permeameter data were consistent with results of the multi-step outflow tests and bounded by the capillary and pressure plate test results, as expected. The retention curves derived from cone permeameter data exhibited more curvature than those obtained from the other methods. The curves obtained from multi-step outflow tests exhibited less hysteresis than those derived from cone permeameter tests and were more repeatable than the pressure plate test results.