Numerical study on the evolution process of slope failure triggered by extreme rainfall along a road-cut in mountainous terrain

Abstract

Modeling the flow evolution of a slope governed by solid mass has been recognized as a challenge, yet most stability analyses are only based on stability number or Safety Factor (FOS). The stability number in most cases does not incorporate the deformation characteristics of the material and the change in solid mass phases such as from solid-like to fluid-like phase. Therefore, the purpose of this study is to present a numerical simulation that describes the failure evolution of a slope with a fault along with a road cut. A finite element method associated with an elastoplastic model with strain softening is adopted to provide a failure evolution of R71 road cut slope instabilities. The results of the study have demonstrated that the present computational framework is capable of quantitatively reproducing the failure evolution process, the final run-out distance of the slope material. The simulation has evidenced that the flow evolution of material during extreme rainfall is expected to extend to the final deposit of 4.5 m, indeed, the field measurements and observations also confirm. Furthermore, the simulations also demonstrated that the distance in which material can reach is largely controlled by the composition and phases of the material undergone during flow evolution. Owing to that, the resistance of material has a major role in the run-out of the material; this resistance of the material is also controlled by shearing and absorbed kinetic energy during the process. The overall conclusion is that, for material to flow for a longer distance, high kinetic energy and more shearing of material are expected to take place during this process. It is recommended that other sophisticated methods could be utilized to further the results.