Study On Risk Assessment Of Debris Flow In China-pakistan Highway

The China-Pakistan Highway is located in the Pamir Plateau,where the terrain fluctuates greatly,the geological structure is complex,and the climate and environment are bad.Since the road was opened to traffic,it has been damaged and blocked by debris flow many times.As the main line of transportation connecting China and Pakistan,the China-Pakistan Highway is also an important channel for the construction of the China-Pakistan Economic Corridor,leading to the South Asian subcontinent and developing the "Belt and Road Initiative" strategy.It is of great economic and strategic significance to carry out the study of debris flow on and along the China-Pakistan Highway.In this dissertation,the debris flow disaster along the China-Pakistan Highway and its route is taken as the research object.On the basis of historical data collection,remote sensing interpretation and field investigation,the risk assessment of debris flow disaster in China-Pakistan highway was carried out by using the spatial analysis and statistical analysis technology of GIS.The main research contents and achievements of this dissertation are as follows:1.The debris flow along the China-Pakistan Highway is interpreted by remote sensing images,the geological and environmental background data of the area are collected,the spatial distribution and regional characteristics of debris flow in the study area are identified,the special maps related to China-Pakistan highway and debris flow disaster are drawn,and the debris flow disaster database is established.It provides data support for subsequent debris flow risk analysis.2.According to the disaster environment and excitation conditions of debris flow on China-Pakistan Highway.Eight main control factors including slope,height difference,land use type,geotechnical type,fault zone density,PGA,annual precipitation and river density,are selected to construct debris flow risk assessment index system.Based on GIS and information model,the hazard zoning and assessment of debris flow on the whole route of China-Pakistan Highway are realized.The results show that 51.39% of the sections of China-Pakistan highway are in the high dangerous area or above,especially in the section from Aoyitage to Bulunkou,the alpine canyon area of Karakoram Mountains and the steep valley section of Chilas complex.3.Based on the historical satellite image,the Flow-R model is used to calculate the runout path of debris flow from Gaizi to Bulunkou of China-Pakistan Highway.The accuracy verification results show that the simulation accuracy of the model is 83.85%.According to the attribute characteristics and harm mode of debris flow,the scale of debris flow,the degree of loose material recharge,the area of gully basin,the length of main gully,the relative height difference of watershed,the cutting density of watershed,the proportion of unstable gully length and the degree of river blocking are extracted as the hazard assessment indexes of debris flow.The risk assessment method based on debris flow movement process is a new exploration of debris flow hazard assessment.Among them,the debris flow N5(Aierkuran gully),N14 and N20,which are located on the same side of the highway,are the most dangerous and the most serious threat to the highway.As far as the cover section of China-Pakistan highway is concerned,the length of the section at very high dangerous,high dangerous,moderate dangerous,low dangerous and potential dangerous is 4.33 km,0.62 km,1.41 km,1.68 km and 11.22 km.4.According to the characteristics of highway engineering and the disaster mode of debris flow in the study area,from three aspects: engineering exposure,highway attribute and disaster recovery ability,the relative spatial position with debris flow,engineering geological background,highway engineering type,height difference between pavement and riverbed,distance from town and altitude,are selected as assessment indexes of highway vulnerability.The assessment indexes are quantified,graded and standardized.The vulnerability zoning of debris flow in China-Pakistan highway is realized by using the multi-factor comprehensive evaluation method.5.Summarize the highway debris flow hazard analysis model based on GIS,information model and the highway vulnerability model considering highway engineering exposure,highway attribute and disaster recovery ability.Realize the risk zoning of debris flow on the whole route of China-Pakistan Highway.The sections of Aoyitage to Bulunkou,Khunjerab to Pasu and Jaglot to Sasin are the three sections with the highest risk of debris flow in China-Pakistan Highway.Production of related thematic maps.The research results can be applied to linear engineering line selection,line optimization and debris flow risk management.