Study On The Typical Soil Landslide Base On Numerical Simulation Of Saturated-unsaturated Seepage In The Area Of Western Yunnan

The western of Yunnan is the focus of large-scale development of the western region, and it is also the main artery leading to Southeast Asia. Red beds in the region is widely distributed, and rainfall-induced landslides are so frequent that have caused tremendous loss to projects and people's living, this paper found out the basic characteristics of Sipu landslide and the main influencing factors by the landslide investigation and experiments, the mechanical parameters and soil-water characteristic curve of clay had also got, Calculated the permeability of unsaturated soils function; by the saturated-unsaturated seepage theory, changes in the process of seepage field were analysis; According to the transient simulation of seepage field and non-saturated shear strength theory, the stability of Sipu landslide and the space-time evolution of the critical slip surface were analyzed. Summed up the main factors that caused the rainfall-induced landslide and the features of the critical slip surface, it can provide important reference to disaster prevention.Based on systematic research on rain-induced Sipu landslide the main conclusions are as follows:1. Special geotechnical structure in Sipu landslide and the clay with interbedded gravel for the landslide provide a good space for groundwater convergence; Strong permeable gravel and gentle slope conditions are conducive to rainfall infiltration; distinct rainy and dry season, concentrated rainfall, desiccation cracking after water content drops and with weak dilatability in clay, all of them are the main factors that induced landslide.2.By experiments, it found that the influence of water content on the clay intension is obvious, based on the push-shear test, the strength parameters were obtained which are close to actual conditions, the cohesion is 20.37kpa, internal friction angle is 10.6°3. The special structural characteristics of Sipu landslide makes rainfall to the impact of the landslide is not an well relations corresponding; under the alternating wet and dry conditions, the first heavy rainfall was on the highest degree of sensitivity to the landslide, landslide is greater affected by the former rainfall characteristics.4.In the influence of first heavy rainfall, the stability of Sipu landslide is rapid decline, as to the third day in the rain the stability coefficient is lower than 1.0,and the landslide is in sliding state, the stability of landslide has lagged behind rainfall about two days. It need quite a long time return to the former stability after rain,5. The critical slip surface of rainfall-induced landslide shows the characteristics of the spatial variation. As rainfall is small, these zone where contact well with the gravel and the front foot of landslide are prone to cause shallow landslides, when in the alternating wet and dry conditions, the continuous heavy rainfall will induce a wide range of surface clay landslide.