The Development Characteristics And Risk Assessment Of Zhuanjinglou Debris Flow In Wenchuan County,Sichuan

Debris flow is one of the most common geological disasters in southwest mountainous area,which is characterized by strong outburst,short duration and great destructive power.On August 20,2019,a large-scale debris flow disaster broke out in Zhuanjinglou Gully,Wolong Town,Wenchuan County,Sichuan Province,which brought huge losses to Zhuanjinglou Village.In order to evaluate the risk of debris flow in Zhuanjinglou Gully scientifically,combined with the disaster characteristics of “8.20” debris flow in 2019,through field investigation and data review,the development conditions and genetic mechanism of debris flow were identified.The risk degree of debris flow is obtained by different risk evaluation methods.The movement process of debris flow is simulated by using DAN-3D software,and the variation characteristics of accumulation thickness and velocity are obtained.The research results of this paper are as follows:(1)Based on the geological background of the study area,this paper analyzes the development characteristics of debris flow from three aspects: topography,material source and water source conditions.The gully topography provides favorable conditions for the convergence of water sources and the start-up of material sources,and then the debris flow disaster breaks out under the condition of rainstorm.(2)According to the standard,the dynamic parameters of debris flow are calculated quantitatively,and parameters such as bulk density,flow velocity,discharge and scale under different rainfall frequency are obtained,which will provide data for the follow-up research work.(3)The evaluation index and weight evaluation method of debris flow movement process are selected,and then the risk evaluation system of Zhuanjinglou Gully debris flow is established.The risk degree of debris flow under different frequency is evaluated by using the evaluation model of Liu Xilin and the evaluation method of gradation assignment based on AHP,and the risk grade is divided according to the result.(4)The three-dimensional model of the basin is built,and the movement process of debris flow with 20-year return period and 50-year return period is simulated by using the software of DAN-3D.The variation characteristics of velocity and thickness of debris flow are obtained.