The Study Of The Permeability Characteristics And Seepage Law Of Landslide Accumulation Body In The Three Gorges Reservoir Area

The reservoir water level has changed periodically since the storage of the three gorges reservoir,the difference of slope permeability is one of the important factors in the deformation of landslide,there are many factors to determine the permeability strength of slope,such as source rock,material structure,etc;In addition,the change of seepage field is also accompanied by the change of reservoir water level,the problems such as groundwater delay and osmotic pressure have considerable influence on the stability of landslide.There are many landslides in the three gorges reservoir area,and the prevention of landslide disaster is imminent,therefore,it is necessary to study the infiltration characteristics and seepage law of landslide accumulation in reservoir area,therefore,we carried out a series of indoor and outdoor experiments,data analysis and statistics,numerical simulation and other methods to comprehensively analyze the permeability characteristics and seepage law of the reservoir area,the main achievements are as follows:1?The number of zigui and wushan in the reservoir area is up to 50%;The landslide volume type is mainly large and medium,accounting for 88%of the sample;The sample landslide is mainly composed of siltstone and mudstone.The landslide body in the reservoir area is mainly permeable medium and benign,and the slope bodies in fengjie,wuxi and zhongxian are mostly permeable,the landslide in fuling,yunyang,wushan and other counties is dominated by good permeability;The average saturation permeability coefficient of the landslide in the reservoir area is2.32m/d,the maximum value is 21m/d,the minimum value is 0.01m/d.The permeability curve is divided into two stages:unsaturated and saturated infiltration.2?The average permeability coefficient of badong is 5.92m/d,and the maximum permeability coefficient of single landslide is 21m/d in fuling,and the minimum value is 0.01m/d in yunyang county;The minimum permeability coefficient of single landslide in each county is less than 1m/d;The lithological composition of the reservoir area is divided into four categories:limestone and dolomite,siltstone and mudstone,marl group and sandstone group,In the four types of lithology,siltstone and mudstone were the main ones,and the number of landslides was 247,which accounted for 62.37%of the total landslide;The material structure of the landslide slope in the reservoir area is divided into the following categories:fine grained soil,soil containing broken stone,earth splint,broken rock,and block rock mass,The maximum range of permeability coefficient of single landslide in five types of landslide is 2.5-21m/d,and the range of the minimum permeability coefficient of monomer landslide is 0.01--2.3m/d.3?Combined with field and laboratory tests,The following cognition is given to the landslide in the red zone of the reservoir area:the more fine particles in the slope,the smaller the saturation permeability coefficient;The correlation between the permeability coefficient and the non-uniformity coefficient and the curvature coefficient of the red zone in the reservoir area is weak,which is a good linear relation with the content of soil gravel,initial moisture content and pore ratio;The permeability coefficient formula of soil fine grained soil in the red zone of the reservoir area is established:K=4.775-5.515X₁+19.405X₂-23.628X₃ The permeability coefficient formula of the mixture of soil and rock in the red zone of the reservoir area is established:???4?Numerical simulation shows that the water level of the reservoir increases with the rate of 1m/d and 1.2m/d,and the greater the permeability coefficient of the slope,the shorter the time of the reservoir water recharge slope,that is,the Angle between the front of the seepage curve and the horizontal direction is smaller,and the longer the time is,the larger the Angle is.The smaller the permeability coefficient,the greater the curvature of the percolation curve,the longer the time required for the water level to be equal to the level of the reservoir,the greater the permeability coefficient,the opposite.The reservoir water level decreases with the rate of 1m/d and1.2m/d.The greater the permeability coefficient,the smaller the Angle between the front end and the horizontal direction of the seepage curve,The shorter the time is,the less obvious the curve is,and the less the permeability coefficient is.5?The reservoir water level rises with the rate of 1m/d,and the stability coefficient of the landslide,cao jia tuo landslide and lying shaxi landslide increases to a certain point and then decreases until it is stable;The higher the permeability coefficient is,the shorter the slope is;The lower the slope permeability coefficient,the higher the stability coefficient value and the larger the maximum value,and the larger the decrease,the longer it takes to reach steady state.The reservoir water level decreases at 1m/d,and the stability coefficient of the three landslides decreases to a certain point and then increases until it is stable.The smaller the permeability coefficient is,the larger the stability coefficient is,the smaller the minimum value is,and the longer it takes to reach steady state.6?The higher the infiltration coefficient,the lower the duration and the decrease of different intervals,it is more conducive to the drainage of the groundwater in the slope,the decrease of osmotic pressure,and the improvement of the final stability of the slope body.