Determination of Mohr–Coulomb Shear Strength Parameters from Generalized Hoek–Brown Criterion for Slope Stability Analysis

Excerpt

Rock slope stability is critical for many aspects of mining and civil engineering projects, such as open pit mining and large dam construction. One of the most popular approaches for estimating the factor of safety (FOS) of a given slope is the limit equilibrium method (LEM) where rock mass strength is usually expressed by the linear Mohr–Coulomb (MC) criterion. Currently, a widely used criterion to estimate rock mass strength is the non-linear Generalized Hoek–Brown (GHB) failure criterion since it is able to estimate the shear strength of various types of intact rock and rock masses (Priest 2005). If the GHB criterion is used in conjunction with LEM for analyzing the rock slope, methods are required to determine the equivalent MC shear strength parameters cohesion c and angle of friction ϕ at the specified normal stress σ _n from the GHB criterion. The determination of reliable shear strength values is a critical step in slope design as small changes in shear strength parameters can result in significant changes in the value of the FOS (Wyllie and Mah 2004). In past decades, methods for the determination of shear strength from the Hoek–Brown criterion for slope stability analysis were proposed by Hoek (1983), Priest and Brown (1983), Londe (1988), Hoek (1990), Hoek and Brown (1997), Kumar (1998), Hoek et al. (2002), Carranza-Torres (2004), Priest (2005), Fu and Liao (2010), Yang and Yin (2010). Comprehensive review of the literature of estimating shear strength of the Hoek–Brown criterion can be found in the paper by Carranza-Torres (2004). However, as Brown (2008) has noted, deriving exact analytical solutions for estimating the shear strength of a rock mass modeled using the GHB criterion has proven to be a challenging task due to the complexities associated with mathematical derivation. …