Jinle Landslide Stability under Water Level Fluctuation of Three Gorges Reservoir

After the operation of Three Gorges reservoir,the water level of the reservoir will fluctuate in the range of 145 m-162 m-175 m.Water level fluctuation will soften the rock and soil on the bank and induce the underground water fluctuation and decrease the shear strength,which will influence the landslide stability.Therefore,landslide stability evaluation under the reservoir running is necessary and important.Jinle landslide is one of the large and complicated landslides in this area.Based on the engineering geological condition investigation results,the formation mechanism is analyzed.The 2D finite element model is developed and the rational calculation parameters of the rock and soil are chosen.With ICFEP software,7 simulations are done according to the reservoir run curve.The results show that: (1) in the natural state,Jinle landslide is stable; (2) when the water level is impounding,the stability of the landslide front edge is better than the corresponding stable water levels; (3) when water level falls,the front edge of the landslide will fail; especially when the water level drops rapidly from 162 m to 145 m the front edge of the landslide will fail,meanwhile it is possible subject to progressive failure in the front and middle parts of the landslide; (4) the deformation and failure of the Jinle landslide is pulling and progressive failure mode.During the first water level fluctuation period,the whole landslide can stay stable.The front part of this landslide should be improved.