Influence of joint spacing and rock characteristics on the toppling stability of cut rock slope through a simplified limit equilibrium method

Abstract

Toppling failure of rock mass/soil slope is an important geological and environmental problem. Clarifying its failure mechanism under different conditions has great significance in engineering. The toppling failure of a cutting slope occurred in a hydropower station in Kyushu, Japan illustrates that the joint characteristic played a significant role in the occurrence of rock slope tipping failure. Thus, in order to consider the mechanical properties of jointed rock mass and the influence of geometric conditions, a simplified analytical approach based on the limit equilibrium method for modeling the flexural toppling of cut rock slopes is proposed to consider the influence of the mechanical properties and geometry condition of jointed rock mass. The theoretical solution is compared with the numerical solution taking Kyushu Hydropower Station in Japan as one case, and it is found that the theoretical solution obtained by the simplified analysis method is consistent with the numerical analytical solution, thus verifying the accuracy of the simplified method. Meanwhile, the Goodman-Bray approach conventionally used in engineering practice is improved according to the analytical results. The results show that the allowable slope angle may be obtained by the improved Goodman-Bray approach considering the joint spacing, the joint frictional angle and the tensile strength of rock mass together.

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