Consistency analysis of Hoek–Brown and equivalent Mohr–coulomb parameters in calculating slope safety factor

Abstract

In slope stability analysis, the Mohr–Coulomb (MC) criterion is usually adopted, however, it has some limitations with regard to the rock mass description. Then the Hoek–Brown (HB) criterion was created and then widely used, and the equivalent Mohr–Coulomb (MC) parameters were proposed. However, the consistency of the HB and equivalent MC parameters in calculating slope safety factor remains to be further explored and confirmed. In this study, the gravity increase method and HB parameters were combined to analyze slope stability, and the calculation results of safety factor were compared with those of equivalent MC parameters in the same conditions. This approach was conducted to explore the parameter equivalence by analyzing the consistency of the two safety factors. Then, the HB parameters and slope height (H), which can cause the safety factor distinction (∆Fs), were studied, and the expression of ∆Fs to influencing factors was tested to examine their relationship. The results indicate the following: (1) The HB and equivalent MC parameters are not completely consistent in calculating the slope safety factor, unless the safety factor is relatively small. (2) The sensitivity of the HB parameters to ∆Fs is GSI > D > mi >σci. Moreover, when H is 20 m or 30 m, each HB parameter is linearly related with ∆Fs, in which GSI, mi, and σci are positively correlated with ∆Fs, while D is negatively correlated. (3) The H is found to be in an inversely proportional relationship with ∆Fs. The ∆Fs decreased in a slow downward trend as the H increased. Simultaneously, the linear relationship between HB parameters and ∆Fs is gradually destroyed by the increase of H.