Estimation of Shear Strength Parameters Considering Joint Roughness: A Stability Case Analysis of Bedding Rock Slopes in an Open-Pit Mine

This study aims to fully explore the influence of rock joint roughness in the slope stability analysis of an open mine. Therefore, based on the least squares parameter estimation method, a generalized shear strength parameter coupling roughness, which is used to evaluate a slope design, was established by a matching formula reflecting the relationship between the roughness coefficient and the shear strength parameter. Firstly, to verify and calibrate the model, physical direct shear tests were conducted on serrated rock joints, and the effect of roughness was analyzed qualitatively. The results show that an increase in tooth height increases the internal friction angle but decreases cohesion. Therefore, the rock joint direct shear test numerical model by PFC-2D was established and compared with the physical test curve, effectively verifying its correctness. The relationship between cohesion c and internal friction angle f with roughness coefficient JRC was further quantified, and the new model was then fitted to characterize the relationship between roughness and shear strength parameters. This method is applied to the design optimization of an open pit mine slope. The new parameters are input to GeoSMA-3D, which is used to search for the key block of a bedding slope on an open-pit mine, to optimize the design of the slope.