Effects of Wetting–Drying Cycles on Strain–Stress Relationship from Triaxial Test of a Mudstone Mixture

Soils filled in or along bank of a large reservoir may be subjected to wetting–drying cycles induced by cyclic lowering and rising of reservoir water level. The wetting–drying cycles may affect the mechanical behaviors of the soils. This study focused on the effects of wetting–drying cycles on the strain–stress relationship from triaxial test of a mudstone mixture. Several consolidated drained triaxial tests with wetting–drying cycles were carried out. Experimental data indicates that the wetting–drying cycles may induce an increment of axial strain, Δε, and a decrement of deviator stress, Δ(σ 1 − σ 3 ). With increment of the number of cycles, N, the values of Δε and Δ(σ 1 − σ 3 ) are increasing along logarithmic curves. Both change rates of Δε and Δ(σ 1 − σ 3 ) are sharply dropping with increment of N value. Thus, the effects of wetting–drying cycles on the strain–stress relationship of test material are mainly concentrated on the period of first several cycles. Based on experimental data, several fitting equations, which may estimate the values of Δε, Δ(σ 1 − σ 3 ), change rates of Δε and Δ(σ 1 − σ 3 ), with increment of N value, were suggested.