Stability Analysis Of Rainfall Induced Slope Failures

Slope is one of the most familiar engineering. The slide slope is one of the three geologic disasters which may lead to much property loss and also many deaths. As the fast development of the economy construction, the study on the stability of slope is of great significance.(1) Utilizing the SEEP/W program, a seepage analysis model is established, and then a series of steady and transient seepage analyses are carried out. By this, discuss two important parameters of unsaturate soil:soil-water characteristic curve and hydrolic conductivity,and its influence on seepage.(2) Analyse the failure mechanism of unsaturated soil slope under rainfall infiltration. Base on strength and deformation theory of unsaturated soil, obtain the stability analysis method of unsaturated soil slope. And, discuss the FEM strength reduction method in slope stability analysis.(3) Base on unsaturated soil mechanics theory, saturated-unsaturated seepage theory, a finite element model is set up, choosing three kind of typical soil:clay, silt and sand. A series of transient seepage analyses are conducted, showing the seepage field and moisture distribution, and its changing within time.Base on this result,get the transient stability of slope safety factor.(4) Based on the modified Moore infiltration model of two layer soil, the process of rainfall infiltration is divided into four process,then discuss at the condition when surface layer's hydrolic conductivity is smaller than subsurface layer's and the reverse is also disucussed. The result of numerical analysis show the pore-water pressure,water content and hydraulic gradient distribution,and verify this four process. Base on this, calculating the infiltration rate-time curve, saftey factor-time curve and rainfall intensity-rainfall duration-deep of wetting font curve. Using this model explain the shallow landslide failure mechanism of bed rock slope.(5) Considering the influence of seepage force calculate the critical deep function of slope failure according to slice method. Combine the function with pore-water pressure curve, the intersection indicate the depth of slope failure in accordance with time. The result show that the depth of rainfall induced slope failure has relation with pore-water pressure distribution only. And further verify the result of one model experiment.