Research On The Influence Of Stratigraphic Texture On Dynamic Response And Instability Mechanism Of Slopes

It’s more than 5000 kilometers from Shanghai to Tibet in the 318 national highway, The geological disasters is serious along 318 national highway in Tibet, Mainly here collapses, landslides and mudslides occurred. Avalanches, bank erosion and the freeze-thaw of frozen soil developed at the same time. The typical geological disasters such as landslide and collapse developed in the section Linzhi county to Bomi county. The study of that earthquakes cause secondary geological disasters in the section will act as a quite important role in the construction of highways and railways.This paper is based on natural fund project" Study of Dynamic Response and Sliding Mechanism of Slopes in Bomi-Linzhi Tibet,G318 National Highway". After widely find out landslide disaster in Bomi-Linzhi Tibet,G318 national highway, and then count out the strati graphic texture type of the landslide. Finally, establish the corresponding numerical model based on the most typical type of the stratigraphic texture. When the seismic dynamic response of the numerical model caused by earthquake has been count out, I studied the law of dynamic response, and analyzed the failure mechanism. So I get the following results:1, The dynamic response rules of the surface of soil layer slope are as follows:With the height increase, the PGA amplification coefficient will also increase, and there is maximum value in a certain height. The PGA amplification coefficient of the slope body present vertical amplification effect; After the earthquake the slope is also stable. But after the quake there is local shear failure in the slope toe which may be a cause of instability and failure of soil slope in the study area.2 The instability and failure state of soil-rock slope is as follows:two potential sliding zone appears in the slope that the soil layer is gravelly soil after the quake, one of the sliding zone is in the interface between the sliding body and the bedrock. The other under the sliding body 10 meters form a through sliding surface. A through sliding surface in the interface between the sliding body and the bedrock is formed in the slope that the soil layer is moraine soil. Tensile crack takes place on the surface of the slope. Shear failure takes place in the toe of the sliding body. Some units occur Tensile crack in the top of the slope that the soil layer is gravel soil.The law of dynamic response of the soil-rock slope are as follows:the PGA amplification coefficient increase with the height, and there is maximum value in a certain height. The PGA amplification coefficient of the slope body show uniform vertical amplification effect, and PGA amplification coefficient oh phyllite slope is larger. In the contact zone between the soil and rock, the horizontal displacement and acceleration response of the soil layer and the rock layer shows obvious difference. The author thinks that this is the root cause that the soil-rock slope often slide in the contact zone between the soil layer and the rock layer. That is to say, the slide is caused by the uncoordinated deformation due to the different response in rock layer and soil layer. PGA amplification coefficient and horizontal displacement of the slope that the soil layer is gravel soils is significantly greater than the slope that the soil layer is moraine soil. Visibly, the extent of the damage of soil-rock stratigraphic texture slope is more controlled by the soil layer type.