Potential Instability Modes and Support Stability Analysis of Soil Accumulation Slopes Along the Lexi Expressway

Geological conditions along the Mabian-Zhaojue section of Leshan -Xichang Expressway are complicated, and during the construction process, landslides and geologic hazards are frequent under the influence of engineering excavation disturbance. In view of the deformation, damage and development and evolution of soil slope under excavation disturbance widely existed along Leshan-Xichang Expressway, taking the soil accumulation body slope on the left side of the section from ZK125 + 654 to ZK125 + 775 along the route as the research object, the potential deformation and damage mechanism and the stability of excavation support were analyzed by using FLAC 3D software. The results show that under the unsupported excavation condition, the slope is mainly dominated by creep-slip deformation of the slope surface; under the unsupported rainstorm condition, the slope undergoes large-scale destabilization damage with excavation. In the excavation and support process, as well as in the rainstorm condition after the completion of support, the stability of the slope as a whole and the support structure are better. The slope is a creep-slip-pulling earth slide in which the rock and soil bodies on the surface of the slope body are sheared off at the potential shear sliding surface in the slope body under the multiple effects of engineering disturbance, rainfall and gravity, and the slope body as a whole is subjected to unloading and traction at the leading edge and squeezing and pushing at the trailing edge, and then it slides along the circular arc shaped shear sliding surface in the accumulation body.