Mechanical Damage Induced by the Water–Rock Reactions of Gypsum-Bearing Mudstone

The deterioration of the mechanical properties of gypsum due to water–rock reactions has attracted extensive attention in the areas of structural geology and civil engineering, and accurately predicting variations in the mechanical behavior of gypsum under different engineering conditions presents a challenging yet intriguing endeavor. In our study, we conducted experimental investigations of the influence of water–rock reactions on the mechanical behavior and mechanisms of gypsum-bearing mudstone. Subsequently, we constructed a mechanical damage model to predict the behavior under varying dissolution times. During the water–rock reaction, water dissolves substances along crystal interfaces and mineral joint surfaces, changing the way particles contact each other, weakening the contact strength, creating intergranular solubility pores, and causing an increase in porosity, all of which lead to a decrease in the mechanical strength of gypsum–containing rocks. The experimental results showed that the maximum decrease in peak strength and cohesion of the samples with the increase in porosity was 69.68