Debris Flow Disaster Assessment And Ecological Prevention In Yanji Gully

Debris flow is one of the most recognized geological disasters.Because of its impact,contingency and explosion,it has a great impact on the safety of people's life and property.In the southwest,the geological environment is complex,and it is the heavy disaster area of landslide debris flow.It is of great significance to study the risk assessment of debris flow to predict and prevent the debris flow disaster.This paper is based on a detailed survey of Yanji gravel debris flow and detailed investigation visits by local residents,as well as a detailed understanding of local weather conditions,geological survey and so on.Based on the above research results,the formation and development characteristics of Yanji area are analyzed by influencing factors of debris flow.The dynamic parameters such as the density of debris flow,the flow rate of debris flow,the velocity of debris flow and the impact force of debris flow in the Yanji gully region are calculated.AutoCAD and MAPGIS software are used to extract the data points of debris flow in the gully valley of Yanji and establish the risk model of debris flow.The fuzzy mathematical evaluation method is used to select the severity of landslides,landslides and soil erosion,the length ratio of sediment along the distance,the accumulation of debris flow in the gully,the longitudinal slope of the river valley and the influence of the regional structure.15 factors,such as degree,river basin vegetation coverage,recent change of the river and lithology,the quality of loose material along the ditch,the slope of the gully slope,the cross section of the sand producing area grooves,the average thickness of the loose accumulation in the sand producing area,the area of the basin,the relative height of the river basin and the blockage degree of the river basin.The BP neural network algorithm is used to select the influence factors of the longitudinal gradient,the area of the basin,the density of debris flow,the length of the gully,the area of the dangerous area and the clay content,and the debris flow gully near the Baihe beach hydropower station is selected as the training target,and the risk degree of the debris flow is simulated by using the MATALB software.Finally,based on the above calculation and analysis results,it provides effective and accurate guidance for comprehensive treatment of debris flow in Yanji gully.Based on the principle of ecological prevention and control,the Yanji gully debris flow is divided according to the debris flow basin,and the different watershed management is carried out.Biological measures are mainly used in clean water area,and biological measures are used as the main part of the circulation area,and the accumulation area is in the middle of the actual situation to choose biological measures.The main conclusions are as follows:(1)The water catchment area of the Yanji gully Valley is 6.0km~2,the average slope of the channel is about 251 per thousand;the loose solid material in the slope surface of the Yanji gully basin is 25 million 315 thousand m~3,and the distribution area is 2.15km~2,accounting for 35.8%of the total area of the river basin.According to the corresponding erosion modulus,about 32 thousand m~3 soil sources are eroded every year;the dry and wet seasons of the Yanji gully are clear and descending.The rainy season is concentrated,heavy rain to frequent rainstorms and abundant rainfall.It has the topography,provenance and rainfall conditions of debris flow.(2)Aaccording to the analysis and calculation,the main parameters of the debris flow in the Yanji gully No.1 gully are as follows:the bulk density of debris flow is 1.45g/cm~3,the flow velocity of debris flow is 3.9m/s,the peak flow rate of debris flow is 30.6m~3/s,the total amount of the first debris flow and the solid substance content are 4 thousand and 800 m~3 and1 thousand and 300 m~3 respectively.The maximum rock mass transported by debris flow is about 97cm,The impact force of the whole fluid is 0.77X10~5Pa.The main parameters of the debris flow in the Yanji gully No.3 gully are as follows:the bulk density of debris flow is1.45g/cm~3,the velocity of debris flow is 3.7m/s,the peak flow rate of debris flow is 18.6m~3/s,the total amount of debris flow and the solid substance content are 2 thousand and 900 m~3and 800 m~3 respectively.The maximum rock mass transported by debris flow is about 88cm,and the overall impact force of the fluid is 0.69X10~5Pa.(3)Through fuzzy mathematical method to evaluate the risk degree of debris flow in Yanji gully,using the discriminant system of"debris flow prevention and control engineering design code"and"debris flow disaster prevention and control engineering exploration standard",15 influencing factors on debris flow caused by debris flow in Yanji gully are selected to evaluate the risk degree of debris flow.Price.It is concluded that debris flow in Yanji gully is a minor debris flow.(4)Through the use of BP neural network algorithm to evaluate the risk degree of debris flow in Yanji gully,by collecting data from other debris flow trenches near the Yanji Valley,the longitudinal gradient,basin area,debris flow density,gully length,area of dangerous area and clay content are selected as the influencing factors of the BP network,and MATLAB software is used to model the model.The result of the calculation is that the Yanji gully debris flow is a dangerous debris flow.(5)Compared with the two methods,the fuzzy mathematical method needs a large number of pre work as paving,but it also brings higher accuracy,which is very effective in the evaluation of a separate regional debris flow,but its own evaluation system is dependent on the weight of experts.The BP neural network method is different from the fuzzy mathematical method.It does not require a large number of relevant data.It generates the desired results by using similar groups to compare data and generate functions.Due to the relatively small selection parameters,the characteristics of many BP neural network algorithms can not be shown in this evaluation.(6)This paper,based on the principle of ecological prevention and control,based on the study of the actual situation in the region,divides the debris flow in Yanji gully according to the debris flow basin,and carries out different degrees of management to different basins.In the clean water area,simple biological treatment is chosen,and the method of combining the plant community with the combination of Joe,irrigation and grass is used to reduce the effect of rainwater erosion,thus postponing the occurrence of debris flow.In the circulation area,because many construction projects are mostly reflected in the circulation area,the management of the circulation area should take into account the rapid safety.Therefore,the circulation area should take the project management as the main part and the biological measures as the auxiliary,mainly by building the drainage channel mainly,guiding the flood disaster which may be induced by the rainstorm,in order to reduce the possibility of the debris flow outburst.The biological measures are mainly aimed at reducing the potential source of debris flow by planting short growing trees with the advantage of dense roots.In the accumulation area,the accumulation area is the sedimentary area of debris flow.The sediments in the area are mostly mixed with silt and big stones.The control of mudslides will be better with densely planted tall trees.