Analysis of mechanical properties and deterioration mechanisms of mudstone under wetting-drying cycles

During seasonal rainfall periods, natural rocks typically undergo repeated wetting-drying cycles, which directly affects the micro-structure of the rock samples and consequently leads to the deterioration of their mechanical properties, especially in mudstone. Therefore, this paper investigated the degradation pattern of strength parameters and failure pattern of mudstone samples under wetting-drying cycles through a series of laboratory tests and quantitatively characterized the micro-structural changes in the samples. Additionally, numerical simulations were utilized to delve deeper into the degradation mechanism of the samples. The results indicate that with an increasing number of wetting-drying cycles, the degradation of peak strength and elastic modulus becomes more pronounced. Moreover, there is a continuous increase in micro-porosity within the samples, accompanied by changes in pore structure and morphology. According to the simulation results, the wetting-drying cycles change how the samples fail, transitioning from mixed tensile-shear failure to predominantly shear failure. This study not only deepens the theoretical understanding of the deterioration mechanisms in mudstone but also provides important guidance for practical applications.