Study On The Stability Law Of Dual Structure Slope In Wenzhou Area Under Rainfall Conditions

China is a vast area with many rivers and rivers.Landslide geological disasters occur frequently.Landslide disasters not only seriously endanger people's life and property safety,but also have a serious impact on local ecological environment,and hinder the economic development of society.Wenzhou is located in the southeast coastal area,with a wide range of mountains,large temperature difference in four seasons and sufficient rainfall,which leads to the strong weathering erosion of the slope in the region,loose rock mass structure,and the influence of rainfall infiltration on landslide disaster in Wenzhou is obvious.For the stability of slope,the object of study is homogeneous soil slope,but the dual structure slope in Wenzhou is more common,but few people study on such slopes.Therefore,this paper will carry out the study of the influence of rainfall on the stability of the dual structure slope in Wenzhou area,which is of great significance to the prevention and treatment of landslide disaster in this area.In this paper,the stability characteristics of binary structure slope in Wenzhou area are studied by means of indoor soil test,numerical simulation and indoor model test.(1)The natural water content,natural density and dry density of typical slope soil in Wenzhou area are 20.07%,1.819g/cm~3and1.515g/cm~3respectively.The cohesion is 21.3k Pa and the internal friction angle is 22.2°?Through liquid and plastic limit tests,it is determined that the typical slope soil in Wenzhou area is low liquid limit silt.(2)The safety coefficient of slope decreases with the increase of slope and the thickness of slope soil.The safety critical value of most slope slopes in natural state is 30 degrees,and the safety critical value of the thickness of slope soil is 3.5m.When the slope or the thickness of the slope soil exceeds these two indexes at the same time,the slope is prone to landslide,so it is necessary to strengthen and prevent them in time.In this paper,the influence of slope gradient,thickness of slope soil and strength coefficient on slope stability is studied by numerical simulation.The results of numerical simulation test show that the safety factor of slope decreases with the increase of slope and the thickness of slope soil.In natural state,the safety critical value of most slopes is 30 degrees,and the safety critical value of slope soil thickness is 3.5 meters.When the slope gradient or the thickness of the slope soil exceeds these two indexes at the same time,the slope is prone to landslide,and it needs to be reinforced in time.(3)With the progress of rainfall,the water content at the top of the slope begins to increase at first.Due to the influence of rainfall infiltration,the erosion failure at the bottom of the slope first occurs,and then a number of irregular arc cracks appear on the slope,and the cracks further expand,leading to the occurrence of slope landslide.The internal displacement of soil decreases with the increase of buried depth,which indicates that the landslide of binary structure slope is a shallow landslide.When landslide occurs,the sliding displacement at the foot of the slope is the largest,so we should pay attention to the protection of the foot of the slope in the process of daily slope prevention.The research results can provide reference for the study of landslide prevention and control in Wenzhou area.