Effects of Wet–Dry Cycle on the Shear Strength of a Sandstone–Mudstone Particle Mixture

Abstract

Shear strength of a sandstone–mudstone particle mixture, filled along the bank of a large reservoir and subjected to wet–dry cycle induced by the rise–lower cycle of water level, may be affected by the wet–dry cycle. To investigate the effects, two-type triaxial tests, without and with the wet–dry cycle, were carried out. The experimental data indicate that the shear strength, denoted by peak deviator stress (σ₁ − σ₃)_f, angle of shearing resistance φ, nonlinear shear strength indicators φ₀ and φ_d, or linear shear strength indicators φ^* and c, is reduced by the wet–dry cycle. With the increment of cycle from 1 to 20, the decrement of shear strength, denoted by the parameters mentioned above, is increasing in a logarithmic relationship. Furthermore, the effect is also related to the confining pressure and stress level selected in the tests. Based on analyzing experimental data, several logarithmic functions, used to predict the shear strength of the mixture after the wet–dry cycle, were suggested. Due to the effect of the wet–dry cycle, stability of a slope, filled in waterfront conditions using the mixture, is reduced.