Study On Deformation Mechanism And Prevention Technology Of Accumulation Landslide Under Rainfall Condition

About 70% of China is located in mountainous areas,and landslide has become the main geological disaster in China under the influence of such special topographic and geological conditions.The research shows that the climate with abundant rainfall and heavy rain is the main factor to induce landslide disaster.In particular,rainfall is the main factor to induce landslide disaster in the process of landslide evolution of accumulation layer.To further study the deformation mechanism of accumulation layer landslide under rainfall conditions and the catastrophic evolution mechanism of slope body after drainage facilities,the model tests were carried out.Taking the Jungong No.3 landslide as engineering prototype,relying on the national key subject(2018YFC1504901),referring to the research results of many domestic and foreign scholars on the model test,and using similar criteria as the test basis,the indoor model tests were established.The deformation mechanism of the slope before and after the well-hole group joint drainage installation was studied in-depth through experimental phenomena and sensors such as earth pressure,water content,and pore water pressure installed in the slope.The conclusions are as follows:(1)The geological survey data and field surveys found that rainfall was the main factor inducing the disaster of Jungong No.3 landslide.The model test deformation phenomenon is more consistent with the prototype slope deformation phenomenon,both of which appear as the whole roadbed subsidence,and the shallow slope deformation of the rear edge is the main test phenomenon.Furthermore,the consistency of the two has an engineering reference for the deformation and destruction process and prevention of actual engineering under the action of rainfall.(2)The decreasing order of earth pressure indicates that the slope deformation under rainfall condition is stratified,and the deformation and failure of the shallow surface soil begin first.The soil deformation at the trailing edge of the sliding body is the largest,so it should be protected in practical engineering.(3)Under rainfall conditions,the soil moisture content and pore water pressure at the foot of the slope are the most sensitive to rainfall infiltration and begin to increase in priority owing to the influence of rainwater infiltration and soil water supply at the back edge.(4)The water content growth curve of the measuring point without drainage facilities was almost "linear",while the water content growth curve was "curvilinear" after the installation of drainage facilities.(5)No matter with or without drainage facilities,the deformation of Jungong No.3landslide under rainfall is mainly shallow slope deformation,and the closer to the top of the slope,the more serious the slope deformation.(6)The comparative analysis of test phenomena,pore water pressure and earth pressure data before and after the well-hole group joint drainage facilities shows that the layout of the drainage facility has a better preventive effect on the deformation of the accumulation layer landslide,which can make the landslide deformation quickly reach stability,inhibit the increase of pore water pressure of sliding zone soil,and improve the stability of slope.