Study On Disaster Mechanism Of Large-scale Accumulation Soil Landslide Induced By Rainstorm

The accumulated soil slope has the characteristics of loose structure and strong water permeability,which is easy to be affected by rainfall and lead to landslides.In this paper,the disaster mechanism and failure process of large accumulation soil landslide induced by rainstorm are studied by means of theoretical analysis,model test and numerical simulation.based on the improved logic regression model,the risk identification method of large accumulation soil landslide induced by rainstorm is established.The main research results are as follows:(1)The indoor model test of large-scale accumulation soil landslide induced by rainstorm is completed,and the influence characteristics of related factors such as different rainfall conditions,slope angle and accumulation time on the failure mode of accumulation soil slope are summarized.the influence law of related factors on the stability of accumulation soil slope induced by rainstorm is obtained.The test results show that erosion slip failure occurs when the slope angle of accumulation body slope is 30 °and the degree of consolidation is 51%;when the slope angle is 60 °and the degree of consolidation is 47%,the comprehensive failure of shallow collapse and erosion slip is easy to occur;when the slope angle is 45 °and the degree of consolidation is 82%,the failure mode is multi-stage retreat landslide failure.(2)through the analysis of saturated and unsaturated seepage,displacement field and slope stability of accumulation soil indoor test model and actual slope model(height 30m),the evolution law of slope deformation under different rainfall intensity is obtained.The results show that the short-term heavy rainfall is easy to increase the shallow pore pressure of the slope and cause the shallow destruction of the slope,while the moisture of the weak rain fully infiltrates into the interior of the slope for a long time,and the slope is prone to deep damage.When the slope angle of accumulation body is 30 °,the critical slip surface affected by rainfall is deeper,and when landslide occurs,the landslide body is larger;when the slope angle of accumulation body slope is 60 °,the collapse failure occurs mainly due to the increase of water absorption weight of topsoil,and the slip surface is shallow.With the increase of accumulation time,the pore pressure of the surface soil of the slope increases rapidly,and shallow landslides are more likely to occur.Under the conditions of light rain,moderate rain and heavy rain,the deformation of accumulation slope is mainly vertical settlement;under the condition of rainstorm,heavy rainstorm and torrential rain,the deformation of accumulative soil slope is mainly horizontal displacement.(3)The rainfall intensity,rainfall time,slope angle and soil permeability coefficient are selected as the probability parameters of accumulated soil landslide,and the landslide probabilities under different rainfall intensity conditions are calculated by Monte Carlo method in SLOPE/W module.On this basis,the property weight function in the standard logical regression analysis method is replaced by the nonlinear function Z=f(t,q,k,i),The function expression is obtained by data fitting of power function,growth curve and other function model.based on this function model,the risk identification method of accumulation soil landslide induced by rainstorm is established.(4)Through the analysis of an engineering example of a slag yard in Shijingshan,considering the continuous rainfall conditions of heavy rain and above rainfall intensity,the landslide risk of the slope continues to increase.after 4 days of continuous heavy rain,the calculation result of landslide probability formula is 92.9%.Landslide risk assessment grade is highly dangerous.This method can quickly identify whether there is a landslide risk in the slag field under the condition of rainstorm.