Characteristic Study On Matric Suction Of Slip Zone After Landslide Control

Rainfall is known as the main factor which affects the stability of slope. During the period of rainfall, water level in the slope will change, the suction and the temporary water pressure will also change with time and rainfal1; At the same time, after constructed the anti-slide piles, retaining wall or drainage structures, whether the nature of slip zone are improved? Anti-slide structure settings maybe affect the natural drainage channel of landslides, which lead to the water table elevation of landslide, then maybe affect the effectiveness of landslide control. This paper discussed the change of seepage-field in the landslide on the different conditions of rainfall infiltration and groundwater level change on the saturated-unsaturated seepage theory and rainfall infiltration. On this basis, the contribution of matric suction to shear strength was considered; the obtained pore-water pressure fields are then input into limit equilibrium analysis program to evaluate the change in factor of safe based on the shear strength theory of unsaturated soil. The main contents and results of this research as following:Firstly, on the basis of analysis of the moisture content which impacts shear strength, the contribution of matric suction to shear strength and the impact of moisture content to shear strength under groundwater level changes was considered by the theory of unsaturated soil mechanics. Then, improving on transfer coefficient method and simplified Bishop method which applied to landslide stability analsis and landslide thrust value calculation.Secondly, model test was preceded, then discuss variable rule on volumetric water content and unsaturated zone and landslide slip, and tested displacement change of sliding structure.Thirdly, based on theory of saturated seepage, the control equation of unsaturated seepage is introduced, and boundary conditions are given on the condition of rainfall infiltration. Analyzed saturated-unsaturated seepage field and the pore water pressure and volumetric water content change under water level fluctuation and rainfall infiltration, and analyzed the contribution of matric suction of landslide slip to shear strength quantitatively.Fourthly, after taken anti-slide pile projects, analyzed the pore water pressure and volumetric water content change in landslide, besides anti-slide pile of following edge and central& upper of landslide slip.Finally, on the basis of seepage analysis, then the impact of intensity of rainfall and water level changes on the stress field and the stability of landslide is discussed,then influencing factors which affecting landslide control is discussed.