Jinle Landslide Stability under Water Level Fluctuation of Three Gorges Reservoir
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摘要: 三峡水库运行后,水库水位每年将在145 m~162 m~175 m间波动,库水位的浸泡软化作用及水位升降引起的地下水位的波动将会降低库岸岩土体的抗剪强度,影响已有滑坡的稳定性.因此,在实际水库运行条件下滑坡的稳定性是目前迫切需要研究的重要课题.针对库区大型复杂滑坡--金乐滑坡,分析了该滑坡的工程地质条件和形成机制; 建立了二维有限元计算模型并选择合理的岩土力学参数; 利用英国帝国理工学院ICFEP有限元软件,依据水库实际运行曲线,在一年时间内分7种不同的模拟状态进行了模拟.结果表明: (1) 金乐滑坡在天然状态下处于稳定状态; (2) 库水位上升状态下,滑坡前缘稳定性较相应的稳定水位状态较好; (3) 水位下降状态,滑坡前缘将出现破坏,特别是162 m下降至145 m时,滑坡前缘出现破坏,存在中前部渐进破坏的可能; (4) 金乐滑坡变形破坏形式为牵引渐进式,在一个水位波动周期内不存在整体滑移的危险.建议对滑坡前缘进行治理.Abstract: 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.
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图 2 金乐滑坡剖面图
1.第四系崩坡积层; 2.中风化底界线; 3.侏罗系中统下砂溪庙组(2~8段岩性组); 4.地下水位线; 5.滑带; 推测地质界线; 7.地质界线; 8.强风化底界线.
Fig. 2. Jinle landslide
表 1 岩土体物理力学参数
Table 1. Mechanical parameters of the model
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