System reliability analysis of joint rock slopes with the stepped sliding surface considering hydraulic and seismic actions.

Based on stepped sliding surfaces, back edge tensile cracks divide the slope bodies into upper (region B) and lower (region A) parts. How region B affects region A, and the instability sequence and interaction relationship between regions A and B need to be further clarified. Based on this, an improved method to analyze the interaction relationship of the two regions is proposed based on the coordination relation of their accelerations. Based on system reliability theory and the possible instability sequence of regions A and B, a slope stability analysis system composed of four failure cases is constructed. Then, the limit equilibrium method and the Monte Carlo method are adopted to analyze the failure probability and dominant failure mode of the slope stability analysis system. In addition, the accuracy of the improved method is verified through comparison with existing theoretical research and discontinuous deformation analysis numerical simulation methods. The results show that with an increase in the fracture connectivity ratios (kA and kB) of the two regions, the slope stability shows a downward trend. In particular, region A is more prone to instability alone with an increase in kA. Region A is more prone to instability due to the interaction relationship because of region B with an increase in kB. In addition, with the increasing of weakening coefficients (Kc and Kφ), ratio of the joint spacing to the slope height (d/H), corresponding parameters of tensile cracks (L/H and β1) and groundwater level (Zw), region A is more prone to instability alone. In contrast, the seismic acceleration coefficients (kh and kv) aggravate the interaction relationship between the two regions and cause a sharp decrease in slope stability. Due to earthquake shaking of water, the seismic force effect on hydrous slopes is more significant with an increase in Zw. [ABSTRACT FROM AUTHOR]