Based on elastoplastic finite element model and Mohr-Coulomb yielding criterion

2D FEM is applied to conduct numerical simulation research of stability of sliding avalanche slope during excavation in navigation route 1+016-1+080 of Longtan Hydropower Station; and the stress and displacement fields

plastic yielding area and effects of supporting system are analyzed. The results of simulation show that there appear continuous deformations during excavation and partly plastic yielding. The changes of groundwater level exert great influence on the slope; but the whole slope is still under stable condition. Meanwhile

the effective supporting measures are critical to improve the stability of slope during the excavation.