The effect of compaction and shear deformation of saturated soil on hydraulic conductivity

Abstract

This paper describes how in a clay soil, consolidation and then shear deformation at a constant porosity affect the hydraulic conductivity of the saturated soil. We used a Bishop and Wesley triaxial cell to consolidate the soil along the normal consolidation line and then to shear-deform the soil at a constant porosity to the point where the critical state condition had been reached. The relationship between hydraulic conductivity (ksat) and soil porosity for soil consolidated on the normal consolidation line was similar to previously published data. However, shear deformation of soil when held at a constant porosity greatly reduced ksat especially at high porosity, where ksat was reduced to 5% of its original value. In dense soil the effects of shear deformation on ksat were smaller. We used previously published water release data for the variously compacted and shear deformed soil to estimate water release curves for the soil in our experiment. We showed that an empirical model to predict ksat gave a good fit to our experimental data collected in the laboratory. We tested the empirical model on a wider set of field data obtained from the HYPRES data base.