Risk Assessment Of Mountainous Rainfall-induced Landslide Basic On Reliability Theory

Fujian province is located in the southeast coast of China,The mountainous area reaches more than 90%of the total land area,residual soil layer is the most widespread.The annual rainfall of Fujian is high,the spring is warm and rainy,and in summer typhoon comes frequency.the rainfall in temperate zone increases year by year as the earth's greenhouse effect become more and more serious.In recent years,the number of rainfall-indueced landslide in Fujian are on the rise,causing huge economic losses and heavy casualties.So the study on risk assessment of mountainous rainfall-indueced landslide has great research significance.Based on the geographic and climate characteristics in fujian province,The rainfall-induced landslide formation mechanism of continuous rainfall and typhoon rainfall are studied through finite element numerical simulation.Analyzed the influence of unsteady seepage flow mechanics to slope deformation characteristics.Combined with rigid body limit equilibrium and reliability analysis theory,the failure probability is selected as the standard of the slope risk assessment,The main contents of study are describes as follows:(1)The data of landslide and rainfall are analyzed through literature research,and summarized the characteristics of rainfall and landslide in Fujian province.Small soil landslide is the most extensive distribution in Fujian Province.It can known that the occurrence frequency of landslide in Fujian province distributed unevely in time and space.The rainfall-induced landslide has strongly severe group features.Rainfall and landslide disasters in fujian province has a spatial and temporal correlation,the extreme rainfall and the number of the landslide has a positive correlation.The rainfall type in Fujian Province can be divided into continuous rains(from April to June)and typhoon rainfall(from July to September)is proposed.(2)Based on the finite element numerical simulation,rainfall type,rainfall intensity and prophase rainfall are selected to studing the influence of slope hazard.Considered the joint action of rain type and rain intensity.Besides,The influence of rainfall on slope infiltration characteristics is calculated and analyzed.Discussed the change rules of infiltration depth,pore water pressure and soil moisture content under different rainfall conditions.Considered the uncertainty of soil parameters,calculate and analys the influence of rainfall on slope hazard,to explore the change law of slope failure probability under different rainfall conditions.Research and evaluate the risk assessment of the slope.The cumulative rainfall can be choosed as the warning reference value of the slope hazard is proposed.(3)The different finite element models are established to study how characteristics of the slope influence the hazard of slope.Slope crack,soil-water characteristic and the layered soil are choosed as the research objects.Based on the reliability theory,the failure probability is selected as the risk evaluation index.Under the Rainfall conditions,simulate the influence of position,depth,width,spacing of crack,value of air-entry suction,pore size distribution,residual water content,saturated volumetric water content and other factors to seepage field.Considering the uncertainty of geotechnical parameters,Discussed the change law of slope failure probability of slope hazard through Monte-Carlo numerical simulation.