Experimental Research On The Formation Process Of Landslide Blocking The River Accumulation And The Chain Disaster Of Failure

There are many alpine valleys in western my country,with active geological tectonic movement,frequent earthquakes,and weathering and fragmentation of surface rock and soil.Under the conditions of heavy rainfall and continuous rainfall,it is easy to induce landslides,mudslides and other geological disasters.In addition,the western region is rich in water systems,which can easily cause landslides Blocking the river chain disaster response.In order to reveal the development and evolution of the landslide blocking the river disaster chain,this paper collects and sorts out nearly 100 landslide blocking river events in Southwest my country in recent years,analyzes the main characteristics of landslide blocking river chain disasters,and develops multi-factor landslide blocking events based on this.The river simulation test conducted research on the evolution,stability assessment,and failure mode of the accumulation body blocking the river after a landslide.The main conclusions obtained are as follows:(1)Through the investigation and analysis of a large number of real landslides blocking the river,it is found that the bank slope angles that are prone to landslides in Southwest my country are mainly concentrated in 30°～40°;small and medium-sized landslides below 3 million m3 account for 35% of the statistics,which are landslides.The high frequency range of occurrence;most of the landslide mass is loose rock and soil.(2)Based on the statistical analysis of the river blocking event,and on the premise of ensuring that the landslide body can slide normally to form a landslide accumulation body,a reasonable landslide blocking river test model device was designed,and different landslide volume,bank slope angle,and landslide body particle size groups were developed.The simulation test of multi-factor landslide blocking the river.(3)Through simulation tests,it is found that creeping layered accumulation and probability zoned accumulation are present in the process of landslide blocking the river.Creeping layered accumulation controls the accumulation area and edge thickness of the accumulation,and the probability zone accumulation controls the accumulation of landslide particles in the same layer accumulation Accumulation sequence: Affected by bank slope angle,landslide volume,and particle group,there are obvious differences in landslide accumulation time and accumulation density,and two different accumulation methods are shown,namely,one-time sliding accumulation and continuous sliding accumulation.(4)Based on the spatial shape,maximum cross-sectional shape,material of the accumulation body and the degree of river blockage of the landslide blocking the river,the difference in the duration of the stability of the accumulation body is analyzed,and a method for evaluating the stability of the accumulation body is proposed and applied to the Baige dammed lake The actual engineering case verifies the accuracy and practicability of the evaluation method proposed in this article(5)The failure analysis of 45 sets of simulation tests reveals that there are mainly three failure modes of landslide accumulation,namely,top erosion,side erosion,and seepage,and the maximum cross-sectional shape of the accumulation has a greater impact on the failure mode;it reveals that the accumulation has a large impact on the failure mode.The impact mechanism of the particle type,square volume,upstream water level rise rate and swell motion state on the collapse and failure of the accumulation body.(6)Combining the upstream water level change,the flow state of the river flow and the particle discharge process of the accumulation body after the formation of the landslide body blocking the river,the three secondary disaster processes and the failure chain that may be induced by the landslide accumulation body blocking the river channel,bank erosion,and debris flow are analyzed.Based on the characteristics of disaster response,it is proposed that strengthening risk assessment and establishing an early warning system are effective measures to cut off the disaster chain.