Mechanical behaviour of soil under drying-wetting cycles and vertical confining pressure

A system for preparing soil specimens subjected to drying-wetting cycles whilst under vertical confining pressures is introduced with Clayey soil specimens subjected to different drying-wetting histories, then the relative performance tested using consolidated undrained triaxial shear tests. Meanwhile, their soil water retention properties were also measured. The experimental results indicate that drying-wetting cycles lead to a rise in the matric suction for soil with high moisture content, and the decrease of matric suction for soil with low moisture content. Partly owing to the higher pore water pressure, peak shear strength reduces gradually during drying-wetting cycles. The impacts of drying-wetting cycles on hydro-mechanical properties of soil specimens during the first cycle are larger than those during the second and the third cycles as the highest matric suction of soil occurs during the first cycle. Vertical confining pressure is shown to limit the impact of drying-wetting cycles on the hydro-mechanical properties of soil effectively because of its restricting effects on the volumetric deformation of soil during the cycles.