| Diaohua gully is located in the southwest of Mao County,Sichuan Province,and is a tributary of the Sanlong River.There are abundant loose solid sources in the Diaohua gully,and the deposits are loose.According to the records,there have been two debris flows.The debris flow have the characteristics of high energy,strong impact and strong erosion ability,which seriously threatens 28 households in Nahu Village?108 persons?,two hydropower stations and a pig farm in the lower reaches of the Sanlong River.In this paper,the Diaohua gully debris flow in Mao County is taken as the research object.Through a large number of on-site investigations and geological surveys,the formation conditions and development characteristics of the Diaohua gully debris flow are analyzed in detail,and the risk is analyzed by numerical simulation.Study and compare the simulation results with the actual results of the field survey.Through comparative research,the more reliable results are applied to the debris flow hazard evaluation and treatment engineering design.The main research results are as follows:?1?According to the field investigation of the research area and consulting relevant literature materials,this paper firstly analyzes the natural geographical environment and geological environment conditions of the research area from the aspects of topography and landform,stratigraphic lithology,geological structure,meteorology and hydrology,etc.Then the starting conditions and development characteristics of debris flow are analyzed comprehensively,and some dynamic characteristic parameters of debris flow are calculated,which provide support for the study of dynamic characteristics of debris flow.?2?Based on the analysis of the development process and characteristics of debris flow in the study area,it is concluded that the source of loose solids in Diaohuagou is abundant and the accumulation body is loose.The catchment area of Diaohuagou debris flow is32.14km2,the maximum relative height difference is 2112m,Debris flow is characterized by high energy,strong impact force and strong erosion ability;There is a very short"blocking-collapse effect"in the process of debris flow migration and this kind of"blocking-collapse effect"mainly occurs in the circulation area.?3?The Diaohua gully debris flow is a torrential rain-type debris flow.It is a low-frequency debris flow from the frequency of occurrence,and the development stage belongs to the development period.Through field investigation,experiment and calculation,the gravity flow of the main gully is less than 1.60g·m-3,which shows the law of severe decrease from upstream to downstream;The flow velocity and flow rate of debris flow are greatly affected by the slope of the terrain.The total amount of debris flow is about 9.64×104m3,and the discharge of solid matter is about 2.97×104m3,which is a medium-sized debris flow in 50 years.?4?Through the Flo-2D numerical simulation method,the mudslide depth,flow velocity and motion state of the Demonstration debris flow at 2%,5%and 10%were simulated numerically,and the simulation results were analyzed and calculated by ArcGIS.The results of the debris flow motion simulation were obtained.?5?The accuracy of the simulation results was verified by the most deficient degree evaluation factor and the percentage relative error:the simulation accuracy is above 70%,and the simulation result has high reliability.?6?Finally,based on the simulation results and the actual situation of the site investigation,after understanding the formation mechanism and development characteristics of the debris flow in the study area,based on a comprehensive analysis of the starting conditions and the characteristics of the hazard object,the prevention and control of the Diaohua gully debris flow is discussed.The management engineering measures of blocking and combining are proposed. |
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