Abstract: To study the strength and deformation characteristics of silty clay during wetting-drying cycles, the undisturbed silty clay is taken from a slope located in Three Gorges Reservoir Region, China. A series of triaxial shear tests are conducted under different load conditions after wetting-drying cycles. The test results indicate that the peak strength, effective cohesion and secant modulus all decrease slowly with the increasing number of wetting-drying cycles. While the effective internal friction angle stays at a steady state. The reason for the deterioration of strength and deformation of the silty clay in wetting-drying cycles is the crack development, which undermines the soil structure. However, external loading can positively restrict the crack development caused by wetting-drying cycles. By fitting the test data, the expression of Mohr-Coulomb yielding criterion for the undisturbed silty clay under wetting-drying cycles is modified.

Key words: wetting-drying cycles, silty clay, load, strength, deformation