Effect of drying-wetting cycles on triaxial compression mechanical properties of sandstone

To investigate the geological hazards caused by the action of drying-wetting cycle on rocks, we conducted a conventional triaxial compression test on sandstone under a high number of repeated drying-wetting cycles. By using the TAW-2000D microcomputer-controlled electro-hydraulic servo triaxial rock testing machine, this study investigated the influences of repeated drying-wetting cycles on the deformation and strength characteristics of sandstone. At the same time, the relationships among the strength, elastic modulus, and confining pressure of sandstone were analyzed. The results show that, when the drying-wetting cycles are relatively low, both the compressive strength and elastic modulus of the sandstone increase with the increase of the confining pressure, and the more drying-wetting cycles are, the more they increase. When the confining pressure imposed on the sandstone is constant and the drying-wetting cycles amount to 10- 15 times, all the compressive strength, elastic modulus, cohesion, and internal friction angle significantly decrease. When the drying-wetting cycles exceed 15 times, the internal friction angle of the sandstone increases first and then gradually decreases. The fractures of the sandstone exhibit a transformation from brittle failure to ductile failure. Under the action of drying-wetting cycles, the sandstone is greatly influenced by the softening action of water soak at the initial stage. The conclusions provide favorable evidence for the analyses of the long-term stability of rock engineering.