Mechanism Damage to Mode-I Fractured Sandstone from Chemical Solutions and Its Correlation with Strength Characteristics

The fracture toughness of rock is very important in rock cutting, blasting, and hydraulic fracturing for tunnel excavation. To evaluate factors that reduce rock fracture toughness, we emulated the environment of joint rock in the hydro-fluctuation belt of a typical bank slope in the Shanxi Tong Chuan reservoir region. We tested long-term immersion of sandstone samples in different chemical solutions to determine the resulting mechanical characteristics and damage degradation. Variations in the physical and mechanical properties of the samples were analyzed under the effects of the chemical solutions. Experimental results show that the sandstone was significantly damaged by the chemical solutions, but its peak strain increased, and different chemical solutions had distinct influences on the degree of mechanical damage. These differences varied with the acid–base properties of the solutions. Also, there were clear consistencies among the solutions in the degree of their damage to mechanical parameters, physical parameters, and ion concentrations. Therefore, we were able to obtain correlations among the physical and mechanical parameters of the sandstone samples, damage variables, and the ion concentrations of calcium and magnesium. The surfaces of the samples were seriously degraded after being subjected to the corrosive effect of various chemicals; for example, there were different amounts of holes and pitting corrosion. The sizes of the holes and the degree of surface pitting gradually increased with an increase in corrosion time.