Influence of confining pressure and structural plane inclination on rock interface slip

This study aims to explore the mechanical behavior of rock masses with structural planes using a mesoscopic perspective. The particle flow code two-dimensional numerical simulation software is employed to investigate the effects of confining pressure and structural plane dip angle on the failure characteristics, mechanical behavior, and slip behavior of rock masses. The research finds that, under constant confining pressure, peak stress and elastic modulus initially decrease and then increase as the dip angle rises, with the minimum values observed at a 65° dip angle. At the same dip angle, both peak strength and elastic modulus increase with increasing confining pressure. For a typical structural plane sample with a 35° dip angle, as confining pressure increases, stress concentration extends from the structural plane, and displacement decreases from top to bottom, with larger displacement at the upper measurement point. As the dip angle increases, rocks transition from tensile to shear failure, then back to tensile failure. Lower confining pressures lead to shear sliding at smaller dip angles. The correlation between dip angle, confining pressure, peak strength, and peak strain is found to be high, approaching 1, while the correlation with the number of fractures is relatively weak. Based on the expression of stress components normal to the structural plane and critical slip conditions, a relationship equation between shear stress and normal stress is derived. This study highlights the role of structural plane characteristics in rock mass failure and provides valuable insights for engineering applications.