| For a long time,as one of the three major geological disasters,landslides have brought huge economic losses and casualties to our country every year,especially in the southeast coastal areas,where rainfall is abundant,which can easily induce large-scale landslides,and in recent years,rural resettlement Housing construction and transportation facilities continue to develop into mountainous areas,which have a certain excavation disturbance to the original natural slopes,which exacerbates the threat of slope instability.Therefore,the stability analysis and catastrophe law of unloading slopes under extreme rainfall conditions are carried out.The research has important scientific significance and social value for the rational selection of rural resettlement housing and transportation network sites in the southeast coastal areas of China,and the prevention and mitigation of site disasters.In this paper,taking the slope of Shangge Village,Pan 'an County,Zhejiang Province as the background,the influence of rainfall and unloading on the slope stability is analyzed theoretically.On this basis,numerical simulation and indoor similar model experiment are used to carry out the stability analysis and disaster law of the unloading slope under extreme rainfall conditions.The main research results are as follows:(1)The change of stress field before and after slope excavation and the process of initiation,expansion and penetration of internal cracks in unloaded slope are analyzed.At the same time,the infiltration rate of rainwater in the rainfall infiltration is analyzed.The rainwater penetrates from the slope surface at a certain rate.When the rainfall makes the rock and soil mass in the saturated state of water absorption in a short time,the cohesion and internal friction Angle of the rock and soil mass will decrease rapidly,and then lead to the occurrence of landslide disaster.(2)Based on the field investigation of the slope in Shangge Village and the data of stratigraphic lithology,hydrology and meteorology of the slope,the main factors affecting the stability of the slope are summarized,and the formation mechanism of the landslide in this region is briefly described.(3)The above Gecun slope is the engineering background,and the discrete element numerical simulation software UDEC is used to perform numerical calculation on the slope stability under extreme rainfall conditions,through displacement analysis,vector analysis and monitoring point data analysis.The results show that the overall stability of the slope is good at the initial stage of extreme rainfall,because the amount of rainwater infiltration is less and does not reach the interlayer fracture zone.With the passage of rainfall time,the amount of rainwater infiltration inside the slope increases continuously and reaches the position of interlayer fracture zone,and the slope stability decreases sharply until the landslide occurs.(4)The process of landslide disaster under extreme rainfall conditions was studied through indoor model experiment.The results show that,after 5h of extreme rainfall,regional cracks in the interlayer fracture zone continue to occur due to a large amount of rainwater infiltration and long-term scouring.After the extreme rainfall for7 h,the slope model formed through cracks at the interlayer fracture zone,and the slope model was unstable.The numerical simulation results were in good agreement with the model experiment results.(5)The whole process of slope instability under extreme rainfall conditions is studied by numerical simulation with different unloading amounts.The results show that the displacement increases with the increase of the unloading amount of slope excavation,and the displacement increases steeply when the unloading amount of slope excavation increases multiples.Due to excavation unloading,obvious stress concentration was formed at the top and foot of the slope,and the magnitude and range of stress concentration increased with the passage of extreme rainfall time. |
PDF Full Text Request