Prediction of soil-water characteristic curves under drying path based on isotropic compression and soil shrinkage tests

Because the soil-water characteristic tests require professional instruments and are time-consuming, the application of soil-water characteristic curves (SWCCs) in engineering design is not popular. Taking three kinds of soils as the research objects, including silty sand, cohesive soil and expansive soil, a simple method is proposed to predict the SWCCs in drying path within the low suction range by performing the isotropic compression tests of saturated soil and shrinkage tests of soil in the laboratory. The research results show that based on the unified relationship between the effective stress and the deformation, the connection between the saturated soil and the unsaturated soil can be established. According to the soil shrinkage characteristic curves under different initial dry densities, the residual water content can be obtained quantitatively by using the curvature formula and the proposed mean value method. The SWCCs within the low suction range predicted by the proposed method are in good agreement with the experimental data obtained in this study. This work contributes to ensure that the unsaturated hydraulic parameters are obtained indirectly when it is necessary to carry out the conventional saturated soil tests.