Limit equilibrium method based on stresses of slip surface for stability analysis of rock slope with introduction of local factor of safety

Because the generalized nonlinear Hoek-Brown(H-B) strength criterion can exhibit the complex shear failure behavior of rock mass, it is widely used in the stability analysis of rock slope. However, the traditional limit equilibrium(LE) methods based on the slice division and assumption of inter-slice forces is not easy to directly introduce the nonlinear strength criterion, which makes the LE methods have some shortcomings in analyzing the stability of rock slopes. In addition, the local factor of safety(FOS) of slip surface is usually assumed as a single variable independent of its position in the analysis of slope stability. In fact, before the slope reaches the critical failure state, the distribution of the local FOS of the slip surface is different. Here, the Taylor series expansion is applied to construct the function of the normal stress on the slip surface, and the function of the shear stress on the slip surface under the linear distribution characteristics of the reciprocal of the local FOS of the slip surface is established to consider the difference of the local FOS of the slip surface. Thereby, the generalized nonlinear H-B strength criterion is integrated with the calculation mode of the stresses on the slip surface and the difference distribution characteristics of the local FOS of slip surface. Thereafter, the stress constraint conditions at both ends of the slip surface is introduced, and then the LE solution of rock slope stability is derived according to the mechanical equilibrium conditions of the sliding body. Through the comparison and analysis of examples, it can be verified that the proposed method can not only accurately evaluate the stability of rock slope under the generalized nonlinear H-B strength criterion, but also reasonably simulate the tension-shear stress zone of the slip surface near the slope top, objectively describe the compression-shear phenomenon of slip surface near slope toe under the stress concentration effect, and effectively distinguish the difference distribution characteristics of the local FOS of the slip surface. Furthermore, in order to facilitate the guidance of design and reinforcement of engineering rock slope, the equivalent curves of the minimum FOS of homogeneous rock slope and the partition diagrams of the difference distribution characteristics of the local FOS of the critical slip surface are drawn. © 2024 Academia Sinica. All rights reserved.