Insights from rock bridge experiments about tensile fracture of the locked section in slopes with stepped joints.

The initiation mechanism of rockslides is crucial to the quantitative evaluation of the slope, especially in slopes containing locked sections. In this study, the analysis focuses on the tensile fracture of locked sections of slopes with stepped joints through rock bridge experiments. Rock bridge experiments under low normal stress were performed on samples containing stepped joints. The cracking behavior of rock bridges, including deformation, strength, fracture mode, and damage, is analyzed from a macroscopic and microscopic perspective. High-angle rock bridges are highly brittle with significant failure precursors. As the angle of the rock bridge changes, shear strength parameters exhibit a negative correlation evolution pattern. Cohesion is lower, and the internal friction angle is higher in high-angle rock bridges. This behavior can be attributed to tensile damage on the failure plane. Different mechanical modes in stress concentration zones trigger varying fracture modes of the rock bridge. Through comparative analysis of rock bridge experiments, slope bottom friction tests, and slope numerical simulations, it is observed that the displacement deflection effect plays a key role in the tensile fracture of rock bridges. The experimental approach provides valuable insights into the tensile failure of locked sections. This research plays a crucial role in elucidating the stepped failure mechanism.