Equivalent Hoek-Brown shear strength for slope stability analysis in highly fractured rock mass

Abstract

In most popular approaches for estimating the factor of safety (FOS) of a given slope, such as the limit equilibrium method (LEM), rock mass strength is usually expressed by the linear Mohr-Coulomb (MC) criterion. However, the non-linear Generalized Hoek-Brown (GHB) criterion is one of the most broadly adopted failure criteria used to estimate the strength of rock masses. In this paper, in order to use the GHB criterion in conjunction with existing slope stability analysis methods based on the MC criterion, approximate analytical solutions for estimating the equivalent MC parameters, cohesion c and angle of friction φ at the specified normal stress σn from the GHB criterion is proposed by using a symbolic regression approach. The results show that the proposed analytical solutions have the merit of producing fairly good shear strength for highly fractured rock mass where the Geological Strength Index (GSI) is less than 40.