Research on a Non-Synchronous Coordinated Reduction Method for Slopes Based on the Hoek–Brown Criterion and Acoustic Testing Technology

Abstract

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; FS = 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.