Natural structural faces often exhibit inconsistent lithology on either side of the rock mass. The study of the shear strength of such heter
Natural structural faces often exhibit inconsistent lithology on either side of the rock mass. The study of the shear strength of such heterogeneous structural surfaces facilitates the analysis of rock stability in complex stratigraphy. Initially, an optical scanning technique is utilized to obtain the point cloud data of natural structural surface morphology and to construct the structural surface mesh model. Subsequently, the model is reconstructed in three dimensions to cast multiple artificial specimens with varying heterogeneous structural surfaces. Direct shear tests are then conducted under different conditions of normal stress and shear direction. Finally, numerical simulations are performed using the simulation software FLAC3D. Based on the JRC–JCS (joint roughness coefficient–joint wall compressive strength) model, the two-dimensional profile method is employed to quantify the structural surface roughness coefficient JRC, and the combined wall strength CJCS (combined joint wall compressive strength) and wall strength coefficient ratio are introduced to reflect different strength combination cases. The results demonstrate that the numerical simulations align more closely with the shear experimental results. When the compressive strength of either the higher or lower side of the structural face is determined, the lower strength side mainly controls the peak shear strength, while the higher strength side enhances it. The effect of $\lambda $ on the peak shear strength is proportional to the normal stress. A nonlinear fitting of the experimental results is conducted to derive a formula for calculating the peak shear strength of the structural face, characterizing the case of different rock strength combinations. The derived strength ratio interval effectively influences the strength of the rock’s structural face. This novel formula extends the JRC–JCS model and can be applied in a wide range of applications.
