| Atmospheric rainfall is one of the main inducing factors of loose accumulation landslide.It is of great significance to study the seepage and deformation failure law of slope under rainfall conditions for landslide monitoring and early warning.In this paper,Xiajie landslide in Sinan County,Guizhou Province is taken as the research object.Based on geological environment investigation and soil physical and mechanical properties test,soil column rainfall infiltration simulation test,rare earth element tracer test,slope rainfall simulation test and numerical analysis test(Geo Studio)are constructed.The evolution characteristics of slope soil structure are focused.Combined with c-characteristic curve model,soil-water characteristic curve model and unsaturated slope stability analysis model,the fine particle migration law and stability evolution characteristics of loose accumulation slope under rainfall conditions are studied.The main conclusions and results of the study are as follows :(1)Landslide geological environment investigation.Through field investigation,the natural and geographical conditions,engineering geological conditions and hydrogeological conditions of the landslide are proved,the basic characteristics of the landslide are analyzed,and the relationship between the formation of the landslide and the characteristics of rock and soil,rainfall infiltration and groundwater activities is preliminarily explored.(2)Physical and mechanical properties test of remolded gravel soil.The physical properties of remolded gravel soil were obtained by physical properties test,and the functional relationship between cohesion,internal friction angle and water content,soil fine particle content was established by direct shear test of remolded gravel soil.The results show that the cohesion and internal friction angle decrease with the increase of water content,and increase with the increase of soil fine particle content.(3)The infiltration law of loose accumulation gravel soil under rainfall conditions.Through the simulation test of soil column rainfall infiltration,the evolution law of soil moisture content,pore water pressure and matrix suction in the process of soil column rainfall is studied by controlling two kinds of factors such as rainfall intensity and particle gradation(permeability coefficient).The empirical formula of wetting front-rainfall duration is established,and the influence law of factors change,the evolution process and mechanism of soil column rainfall are summarized.(4)The fine particle migration law of loose accumulation slope under rainfall conditions.Through slope rainfall simulation test and numerical analysis test,the migration law of fine particles in loose accumulation slope under rainfall condition was studied.The results show that under rainfall conditions,the slope is affected by runoff and seepage,and there are often fine particle aggregation areas at the top,toe and sliding zone of the slope,forming an arc-shaped fine particle aggregation surface inside the slope.The migration and aggregation of soil fine particles are proportional to rainfall intensity and rainfall duration,and inversely proportional to relative density and migration path.(5)The stability evolution characteristics of loose accumulation slope under rainfall conditions.The evolution characteristics of soil moisture content,pore water pressure,matric suction and stability in the process of slope rainfall were studied by slope rainfall simulation test(controlling rainfall intensity,relative density and bedrock surface inclination)and numerical analysis test.The unsaturated infinite slope stability analysis model was improved,and the influence law of factor change,slope rainfall deformation failure mode and mechanism were summarized. |
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