Experimental study on influence of wetting-drying cycles on mechanical characteristics and damage of red sandstone

In order to study the mechanical properties and damage deterioration of the red sandstone coal mine shaft and roadway during thewetting-drying cycles, the red sandstone was subjected to different cycles of wetting-drying cycles, and then compression tests were performed on the MTS815 rock mechanics tester. The study showed that the red sandstone wetting-drying cycles with increasing number of times, the structure changes from dense to porous, the microfissure compaction stage increases in duration, the plastic yields significantly, the peak strain increases, the elastic modulus decreases, and the peak strength decreases significantly, but the strength does not decrease all the time but tends to added to a certain value; under uniaxial compression ten cycles of wetting-drying cycles, the plastic deformation characteristics are obvious; with the confining pressure increases, the duration of the compaction phase decreases, the peak strain decreases, the elastic modulus increases, the peak intensity gets larger as a result, the post-peak plastic deformation is significant and the residual strength is reluctantly increased.Based on the laws of thermodynamics and the principle of energy dissipation, the damage evolution equations and experimental results of red sandstone under different cycles of wetting-drying cycles are similar. The research results can provide parameters for well wall and roadway design and support.