Study on the Evolution Law of Rock Joint Stiffness Under Different Stress Conditions and Its Application

Slip behavior of planar discontinuities in rock masses is the basis of rock slope failure and fault movement. Local failure at different locations of the slip interface occurs before global slip failure, and a precursor signal [acoustic rock joint behavior (elastic stiffness, transmitted wave amplitude, etc.)] is generated. Therefore, detecting the precursor signal before shear stress reaches its peak can be used to predict the instability of rock slopes and fault slip in the macroscopic range. The composition of rocks, distribution of stress, roughness of joints and fault interfaces, and non-uniform distribution of the actual contact area are the primary factors that control the friction strength and slip behavior of joints. The combined influence of these factors enhances the complexity of monitoring local precursor signals. The distribution of rock joint stiffness has previously been obtained based on the elastic wave measurement method to determine the parameter characterization of rock joint contact behavior. Here, the evolution law of joint stiffness during uniaxial compression and shear was studied through laboratory tests and used to analyze the local contact state of rock joints and faults through the change of joint stiffness. A continuous and nondestructive monitoring method is proposed.