Effects of Viscous Property and Wetting on 1-D Compression of Clay and Model Simulation

A series of one-dimensional (1D) compression tests on compacted kaolin powder were performed to evaluate the combined effects of the viscous property and wetting on the elasto-viscoplastic deformation of soil. In the tests, both creep deformation and collapse deformation due to wetting were allowed to take place at various fixed stress states during otherwise monotonic loading at a fixed strain rate. Combined effects of the viscous property and wetting on the stress-strain behaviour observed during 1-D compression were described by incorporating the wetting effects into a non-linear three-component elasto-viscoplastic model (a 3C model). Based on the experimental results, the effects of wetting on the inviscid stress and the irreversible strain relation of the plastic component of the 3C model and the property of the viscous component, having an Isotach property, are formulated as a function of the degree of saturation. Complicated rate- and time-dependent stress-strain behaviour observed during saturation at a fixed stress state and subsequent monotonic loading at a constant strain rate were successfully simulated.