滑床渗透性对超覆型库岸老滑坡稳定性的影响

超覆型库岸老滑坡滑床前缘大多发育一砂卵石层,该砂卵石层的强渗透性将影响滑坡渗流场,从而影响滑坡的稳定性.以三峡库区万州中学老滑坡为例,在确定该滑坡中地下水作用模式为承压水含水层作用模式的基础上,假定砂卵石层的4种不同渗透系数,来研究在库水位波动条件下,滑床砂卵石层渗透性对滑坡稳定性的影响.分析表明,超覆型老滑坡砂卵石层的渗透系数不同,滑坡中浸润线也不同,渗透系数越小,浸润线越低,滑坡中地下水相对库水位的滞后效应越明显；库水位上升阶段、高水位运行阶段和下降初期,万州中学老滑坡各级滑坡的稳定性系数随砂卵石层渗透系数k2的增大而减小；库水位稳定在150 m时,老滑坡整体稳定性随k2的增大而增大,k2的变化对次级滑体和三级滑体的稳定性影响不明显.这对于库区老滑坡的复活和监测预警工程有较强的应用价值.

Effect of Sliding Bed Permeability on the Stability of the Overlap Researvoir Old Landslide

The overlap reservoir old landslide develops mostly on sand and gravel layer at the advancing edge.The strong permeability of the layer will affect the flow field and the stability of the landslide.In this paper,the Wanzhou Middle School landslide was taken as an example.The groundwater model of the landslide was determined the confined aquifer model.On the assumption of the four different permeability coefficient of the sand and gravel layer,we studied the effect of the permeability on the stability of old landslide under the condition of the reservoir water fluctuation.The results show that the phreatic surface of the landslide is different with the different permeability of sand and gravel layer.If the permeability coefficient is smaller,the surface is lower in the landslide,and the lagging effect of groundwater on reservoir level is more obvious.In the time of reservoir water rising,high level and early decline,the factor of safety of the landslides,old and secondary and tertiary landslide,are decreasing with the increasing of the permeability coefficient.When the water level is 150 m,the stability of the old landslide is increasing with the increasing of the permeability coefficient,and the change of the stability of the secondary and tertiary landslide is not obvious.It is of great applicable value to the improvement of old landslide monitoring and prediction.