Seepage Analysis And Unsaturated Soil Water Characteristic Test Of The Landslide Mass In The Three Gorges Reservoir Area

Deposit landslide widely distributed in nature,it's particularly common in the three gorges reservoir area.Deposit material lithology is mainly composed of gravel stone,gravel,earth-rock aggregate that the residual product and diluvial,collapse landslide formed.According to statistics,the wading landslide in three gorges reservoir area are composed of different types of earth-rock mixture.Earth-rock mixture has both the relevant mechanical properties of rock and soil,so it also has the characteristics of unsaturated soil,it can be called special unsaturated soil.In the process of rainfall and reservoir water level fluctuation,the slope body material will experience the process from wet to dry,from wet to dry again and such a process from unsaturated to saturated,from saturated to unsaturated again.The seepage and stability of the deposit is closely related to the characteristics of unsaturated slope.Therefore,the research of unsaturated soil-water features and seepage analysis of unsaturated earth-rock mixture have important value to geological disaster prevention and civil engineering construction.The main works and achievements are as follows:1.At first,the article has carried on the detailed statistical analysis to sliding body material of the three gorges reservoir accumulation landslide,the sliding body of 98% of landslides in the area is earth-rock mixture,and landslide that gravel content in more than 20% accounted for 87%.Sliding body mainly composed of gravel soil and stone soil or silty clay clip to(including)gravel,clip to(including)of stone.2.On this basis about soil water characteristic test of typical landslide,the indoor samples are classified,through the pressure plate apparatus,laboratory test has achieved more than soil water characteristic curve.The paper analyse the effects of gravel size,gravel content,particle size distribution,dry density and plasticity index on soil-water characteristic curve,draw the two factors of smaller crushed stone size,more gravel content and the two factors of less dry density,less plastic index has the same influence on soil water characteristic curve.3.Based on the Fredlund & Xing(FX3)model,Values of the three characteristic parameters in the model has certain regularit as the change of material structure,use the SPSS software regression analysis to deduce a simple calculation function of the three characteristic parameters,come up with the method through indoor basic physics experiment to get the landslide mass soil water characteristic curve,this method has a certain practicality.4.Through matrix suction test of typical landslide field,conclude the soil water characteristic curve of site soil.It is compared and analysed the curve of using formula to calculate and the curve of laboratory test.It is concluded that the soil water characteristic curve of using formula to calculate can be better to response the real situation,and illustrates the reasons of different parts.5.Finally,the curve of used formula to predict the soil water characteristic was applied to the typical landslide,through numerical simulation to analyse the characteristics of seepage field.The underground water level of two typical landslide have varying degrees of hysteresis.The main factor of variations of the concave and convex of affecting the slope of the underground water level aresaturated infiltration coefficient of Sliding body material,unsaturated permeability coefficient function,slope gradient and the length of seepage path.