Study On The Stability Of Red Soil Slope On The Left Bank Of Xiaobanbi Reservoir In Yuanjiang, Yunnan

Because laterite has its own unique engineering geology,and the engineering geology is different under different conditions,it is difficult to objectively evaluate the stability of existing slope stability research methods by using a certain method.At the same time,due to the change of hydrogeological conditions after the impoundment of the reservoir,the stability of the red soil slope will continue to deteriorate,and the overall slope rock mass will be destabilized.Therefore,this paper uses the medium-sized red clay slope at the left bank of the Xiaolanbi Reservoir in the upper reaches of the Che River in the southwestern margin of Yuanjiang County,Yunnan Province?geographical coordinates of 101o46?29?east longitude and 23o30?13?north latitude?as the engineering background.Based on the geological survey of the Xiaolangbi Reservoir in Yunnan Province,the stability of the slope was calculated using the limit equilibrium method and the FLAC^3D numerical simulation software.And in this paper the characteristics of red soil and typical slope stability in the study area were studied in detail.The main research results are as follows:?1?Based on the investigation of geological hazards,this paper makes a detailed study on the development of geological hazards of red soil slopes in the study area by collecting data,engineering geological mapping,drilling and other comprehensive survey means.It is found that the broken rock and soil,the steep topography,intense neotectonic movement and abundant rainfall in the study area provide good conditions for the development of geological disasters.The study area is a extremely high geological hazard prone area.The slope is in an unstable state and its instability will directly affect the safety of the reservoir,making the reservoir silt up and the rapid decline of the accumulation body will cause serious damage to the dam and even imperil the lives and property safety of the downstream people.?2?The slope landslides studied often occur in laterite layers.According to the analysis of mineral composition of laterite in laboratory test,it is concluded that the red soil has coarse grain size,less clay content,low void ratio,less water content,medium plastic shape,moderate compression.It's main state is plasticization-hard plastic.The internal friction angle is large.The cohesion is small and there is no dilatancy and shrinkage generally.According to the analysis of the physical and mechanical properties of laterite,the sandy soil in the study area has been seriously dehydrated and hardened through the action of laterite.The resulting red soil has low compressibility.Under low confining pressure,dilatancy failure appear,while under high confining pressure,shear failure along cementation appear.?3?The reason of slope sliding failure lies in the change of engineering property of laterite.On the one hand,the change of moisture content leads to serious clay particle silting.At the base of the foundation,the clay layer of the red soil layer softens.The engineering properties of the transition zone between the slope soil and the bedrock interface vary greatly,which results in the slope sliding along the interface between the soil and the bedrock.On the other hand,due to the difference in the water content and the loss of water between the upside and downside of the slope after the reservoir impoundment,engineering properties like the specific gravity of slope soil,compression coefficient,modulus of compression,cohesion,internal friction angle and shear strength of the slope soil are different,making the upper soil layer of the slope shrink,crack or even destroy the slide.Because of the erosion of the river,it is easy to form an empty surface at the bottom of the slope,which results in local unloading and then the slope sliding.?4?by using parameter inversion and geostudio calculation,the stability coefficients of landslide under natural and rainstorm conditions are 1.049 and 0.937.The landslide is in unstable and unstable state,respectively.The landslide stability coefficient of natural and rainstorm conditions obtained by FLAC^3D numerical simulation is 1.03and 0.802 respectively.The landslide sliding is more likely to occur under the earthquake condition.The two methods combined with the analysis of landslide stability can achieve good results.