Stability analysis of excavation process of high-steep slope considering unloading deterioration effect

Abstract

Instability and improper protection of the secondary excavation about the slope is one of the key challenges during the reconstruction and expansion of the existing road. The excavation of rock and soil will cause secondary disturbance to the existing slope. Variations in strength parameters of rock and soil materials is found as a result of the excavation unloading. This unfavorable condition often cause the stability of the slope. Adopting the traditional design concept, the existing codes treats rock and soil as ideal elastic-plastic materials without considering the unloading deterioration effect of slope rock and soil materials. However, this practice is not consistent with practical projects. In this paper, based on the secondary development of FLAC^3D, the embedded program for unloading deterioration effect of rock and soil materials during the slope excavation is developed and realized. Then, the stability analysis of high-steep slope for the processing considering the deterioration of rock and soil mass parameters caused by unloading is performed. The result show that the maximum unloading amount in the slope excavation process can reach about 90%. After considering the unloading deterioration effect, the potential failure mode and safety factor change process of the slope during the excavation process are quite different. The unloading deterioration effect greatly reduces the rock mass parameters of the new slope, resulting in the failure of shallow landslides in the local area of the new slope in the later stage of slope excavation; compared with the ideal elastic-plastic slope model without considering the unloading deterioration effect, after considering the unloading deterioration effect, the safety factor of the slope decreases in different proportions, and the gap between them can reach about 20%.The research on the excavation of high and steep slopes considering the effect of unloading degradation can provide a reference and theoretical basis for the excavation design and stability control of high and steep slopes during construction.

Keywords

high-steep slope / reconstruction and extension project / unloading degradation / stability analysis / numerical calculation