Yongming Zhao

Conventional slope stability analyses often rely on two-dimensional models, which neglect local geological heterogeneity and spatial distribution of materials. This simplification can lead to inaccuracies in evaluating slope safety. Additionally, traditional strength reduction methods (SRMs) uniformly reduce the parameters of rock and soil, failing to represent the actual degradation process during progressive failure. This study aims to improve the accuracy of slope stability analysis by developing a method that better captures the spatial variability of geological conditions and the nonsynchronous degradation of shear strength. A three-dimensional (3D) geological model was constructed to restore the actual stratigraphic structure of the slope. Based on the shear strength degradation mechanism, a nonsynchronous coordinated reduction (NSCR) method was proposed, incorporating advanced reduction steps (n) and a correlation factor (λ). This method simulates progressive slope failure more realistically. An engineering case study demonstrated that the 3D NSCR method obtained a safety factor of Fs = 1.265, which is very close to that of the most critical two-dimensional limit equilibrium method section (with a difference of about 1%), whereas the traditional SRM and the two-dimensional coordinated reduction method show relatively larger errors. The 3D analysis revealed the overall dangerous slip surface, providing enhanced insight into slope instability mechanisms. The proposed NSCR method, supported by 3D geological modeling, improves the accuracy of slope stability analysis by better representing progressive failure. It is a feasible and effective tool for engineering applications involving complex slope conditions.

In the process of the evolution of rocky slope instability, the decay deterioration rate of cohesion c and internal friction angle φ are different, and there are also differences in the order and degree of their impact on slope stability; thus, it is of great theoretical value to propose a more practical calculation method for the reduction in slope degradation. This paper combines the Hoek–Brown criterion and an acoustic test method to estimate the mechanical parameters of slope rock mass; the correlative relationship within the double-strength parameter reduction was established by introducing advanced reduction steps (ARS), n, and correlation factor, λ, and a non-synchronous coordinated reduction (NSCR) method for the double parameters of slopes was proposed. Furthermore, methods for determining the comprehensive safety factor (CSF) of slopes during the coordinated reduction of double parameters are comparatively analyzed. The results of the application of engineering examples show that the strength of the slope rock mass is significantly reduced after several blast disturbances, and the equivalent cohesion is reduced from 1.05 MPa to 0.89 MPa, while the internal friction angle is reduced from 25.68° to 21.77°. The CSF calculated using the W. Yuan-2 method is closer to the results of the limit equilibrium method and is suitable for the calculation of the CSF of the NSCR of slopes. The slope CSFs show a trend of first increasing and then decreasing with the increase in n; F_S = 3.349 when n = 50, with a relative error of only 8.1% compared to the results calculated using the limit equilibrium method. The NSCR method remediates the blindness of the traditional strength reduction method in double-parameter reduction and ensures that the reduction range of the internal friction angle is no lower than its residual strength limit value, making it practical and feasible for slope stability analysis.