| During the development and construction of mountain areas,a special kind of geological disaster--debris flow is often encountered.The movement carries a lot of sand and stones,and when it happens,it can be very destructive to objects in its dangerous range,because its movement is very energetic and fast.In the southwest mountainous area high mountains and steep,hydropower projects are often built in the mountains and valleys of the place,due to the limitations of the terrain,near the dam site to take advantage of the site is very small,but the process of the construction of hydroelectric power station it takes many vacant site to arrange various building facilities and personnel placement of hydropower.Therefore,often used near the dam area near the mouth of debris flow arrangement and resettlement of hydropower staff.In this paper,the Lancang River Toba hydropower station Zhonglu debris flow ditch as the research object,through field investigation with remote sensing images,the formation conditions and characteristics of river basin are analyzed,a detailed survey of its source,auxiliary Arcgis,Autocad software,using the combination weighting fuzzy comprehensive evaluation method for risk assessment the Zhonglu ditch debris flow,combined with the Liu Xilin evaluation model and analysis.FLO-2D is used to simulate the Zhonglu ditch debris flow.The movement of debris flow under 4 different frequencies is simulated,so that the mud depth,velocity,area and volume of debris flow can be obtained.Then,establish the risk classification standard of the Zhonglu ditch debris flow,and get the dangerous zoning map of the Zhonglu ditch.Finally,put forward the prevention and control suggestion to the Zhonglu ditch.This thesis studies from the following four aspects:(1)A very detailed field survey was carried out to analyze the development of the Zhonglu ditch debris flow.(2)The forming conditions of the Zhonglu ditch debris flow are analyzed,the study area is a mountain on overall terrain landform erosion,gully slope on both sides of a steep slope,moderate vegetation coverage,material source based on detailed field investigation and remote sensing images,statistics of the type and quantity of the trench source,then carry out the characteristics of basin of the Zhonglu ditch a careful description,through on-site particle analysis experiment,get the accumulation fan size composition,particle content curve drawing and the percentage of the histogram,so as to obtain the size distribution of soil particle distribution and particle parameters.According to the on-the-spot visit,the activity history of the Zhonglu debris flow ditch was visited and its development trend was analyzed.(3)On the basis of on-the-spot investigation and combined with the 1:50000 topographic map,to some parameters such as the Zhonglu debris flow ditch length,average longitudinal slope and elevation were obtained.Fuzzy comprehensive evaluation method is used to evaluate the risk of the combined weight of the Zhonglu debris flow ditch,mainly from the selection of evaluation factors of debris flow disaster history,topography,meteorology and hydrology,human activities and so on,a total of 10 evaluation factors,the calculated results for the degree of risk,and combined with the Liu Xilin model for analysis and evaluation.(4)In order to be more intuitive to reflect the risk of the Zhonglu ditch debris flow,using FLO-2D numerical simulation software under different rainfall frequency(P=0.5%,P=1%,P=2%,P=5%)out of the scale,speed,depth of accumulation,accumulation range.Then,the numerical simulation results of 20 years have been analyzed respectively from accuracy and accuracy,which shows that the simulation results are very good.The dangerous grade classification standard of the Zhonglu ditch debris flow was established,and 4 dangerous zoning maps of recurrence period were obtained.In view of the above research results of the Zhonglu ditch debris flow,some suggestions are put forward for prevention and control of debris flow. |
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