Chemical Weathering Effects on the Dynamic Mechanical Properties of Black Shale Slip Zone under Acid Erosion Action

Abstract Water-rock interaction and intense chemical weathering often lead to stiffness reduction of the slip zone inside the rock slope, which plays a significant role in the evolution of slip zone, especially for the clay-type rock in acidic environment. This study aims to estimate the evolution of dynamic shear strength parameters of this slip zone in acidic environment. Field geological investigations and indoor experimental analyzes, including mineral content variation analysis and dynamic triaxial tests, were conducted in this study. The findings indicate that both the dynamic shear modulus and the damping ratio of the black shale slip zone soil exhibit a significant decrease as the pH level declines. In contrast, the duration of acid erosion appears to have a less pronounced effect on these properties. This finding may provide a novel concept to monitor the strength degradation inner the shale slip zone of bedding rock slopes from a geochemical perspective, in addition to geomechanical methods.