Analysis Of The Influence Of Dominant Flow On The Stability Of Unsaturated Soil Slope

The main reason of rainfall-induced slope instability is the decrease of soil strength. The decrease of shear strength is mainly controlled by the increase of soil water content and soil stress anisotropy. The rate and size of soil water content increase are mainly determined by the inherent permeability ratio of soil and rainfall intensity. Besides, the inherent permeability ratio of soil becomes anisotropy due to the structure and stress anisotropy of soil which are induced by soil sedimentary history, so that rainwater in the slope becomes anisotropy seepage which changes the shear strength of the soil; the initial stress condition of natural soil is generally anisotropic stress condition(coefficient of earth pressure at rest of normal consolidated soil is generally lower than 1), so that the shear stress increment which causes soil destructed required varies in different directions loading condition, and makes soil shear strength decreased. In view of this, this paper mainly analyzes the stress-induced shear strength anisotropy and permeability anisotropy of rainfall-induced unsaturated soil slope stability.This paper proceeds from the basic theory of saturated and unsaturated soil and starts to study the anisotropy of shear strength induced by stress and its impact on unsaturated soil slope stability and compare with an engineering example; then uses Geo-studio software to simulate the preferential flow caused by rainfall in permeability anisotropic unsaturated soil to analyze the effects of soil anisotropic stress condition and soil structure anisotropy on permeability anisotropy, and studies its impact on the safety factor of rainfall-induced unsaturated soil slope; Finally, extends the safety factor iterative analysis method of the stress-induced shear strength anisotropic unsaturated soil slope to the stability analysis of permeability anisotropic unsaturated soil slope to analyze the problem of the stress-induced shear strength anisotropy and permeability anisotropy of rainfall-induced unsaturated soil slope stability. The main research contents and results are as follows:1. Analyze the relationship between triaxial unconsolidated-undrained strength indexes of saturated soil and the strength indexes of another strength experiments.2. Based on the Geo-studio software, Innovative proposition a safety factor iterative analysis method of the stress-induced shear strength anisotropic saturated soil slope and compare with the stability of a seawall in Zhejiang province.3. Through Geo-studio software, analyze the rainfall-induced wetting front migration in unsaturated soil and the preferential flow in permeability anisotropic unsaturated soil.4. Compare the safety factor of the permeability anisotropic and permeability isotropic unsaturated soil slope in the rainfall condition and analyze relationship between safety factor and rainfall duration.5. Through a numerical example, analyze the impact on the safety factor of rainfall-induced shear strength anisotropic caused by stress and permeability anisotropic unsaturated soil slope.