Risk Assessment Of Debris Flow Disasters In Long-distance Oil And Gas Pipelines Based On GIS

In order to ensure the safe operation of long distance oil and gas pipeline in mountain area,risk assessment,prevention and control of debris flow geological disaster are particularly important.By assessing the risk of debris flow geological hazards in long-distance oil and gas pipelines,the risk degree of the pipelines can be obtained more accurately and efficiently,so as to provide basis and reference for the prevention and control of debris flow hazards in pipelines.At present,in terms of risk assessment of debris flow hazard in long-distance oil and gas pipelines in China,there are few quantitative evaluations and more subjective evaluation methods are used in the evaluation process.In addition,the spatial relationship between pipelines and natural environment and disaster reduction facilities are not considered in the assessment of pipeline vulnerability.In view of the above problems,it is of great practical significance to carry out risk assessment of debris flow,pipeline vulnerability assessment and risk assessment of pipeline debris flow in the crossing area of long-distance oil and gas pipelines.In this paper,guangyuan section(82km)of lancheng yuchang oil and gas pipeline is selected as the research object,and guangyuan area and the area related to pipeline crossing are taken as the research area.Through the study on the references and field investigation,collection of the natural environment,geological disasters in the study area,vegetation,hydrology,such as basic data,analysis of the long distance oil and gas pipeline crossing areas of the law of the debris flow hazards and conditions,as regional debris flow risk assessment unit of small watershed,build the index system of regional debris flow hazards,and based on Logistic regression model of regional debris flow hazard assessment model,and the various river basin units to conduct risk assessment and hierarchy;Then use the synthetic evaluation of segmentation method for pipeline unit division,through to the pipeline body data,spatial relationship with natural environment and disaster mitigation facilities distribution analysis of the factors such as building under the action of debris flow pipeline vulnerability evaluation index system and model of pipeline vulnerability assessment based on entropy weight method,and the pipeline vulnerability assessment and hierarchy;Finally,debris flow risk assessment results and pipeline vulnerability assessment results are used to evaluate and grade debris flow risk of long-distance oil and gas pipelines,and finally a complete risk assessment system of debris flow in long-distance oil and gas pipelines is summarized.The main conclusions of this paper are as follows:(1)using Logistic regression model,selection of elevation,slope direction,slope,relief,NDVI,annual average rainfall,lithology,fault distance eight evaluation index for debris flow risk assessment,high risk and high risk areas are mainly concentrated in the temple township township,three heap town,northwest area,such as the high number of danger and identified as high risk zone debris flow accounted for 77%of the total in the study area,in conformity with the research in debris flow has happened.(2)selecting pipeline defect density,pipe wall thickness,buried depth,the Angle of the pipes and the slope unit,pipe location,distance from high-speed,pipes,water transport distance,rainfall stations distance,the distance from levee engineering nine indicators,pipeline vulnerability assessment model is established by applying the method of entropy weight,vulnerability assessment and classification of the pipes.In the evaluation index,the density of pipeline defects accounts for the highest weight,and the monitoring of pipeline body protection and damage should be strengthened.(3)the risk degree and risk level of pipeline debris flow evaluation are calculated by combining the risk degree of debris flow with the data of pipeline vulnerability with the theoretical method of risk evaluation.The results showed that the number of low-risk segments was 53,the number of medium-risk segments was 100,the number of high-risk segments was 22,and the number of extremely high-risk segments was 5.In the southern region of the study area,debris flow disaster is more likely to lead to pipeline damage,so the monitoring of natural environment and pipeline body changes should be strengthened.