Geological Disaster Susceptibility Assessment Along Expressway In Southwest Mountain Area

In recent years,in order to promote the economic development of ethnic regions in western Sichuan Province,the state has planned a number of expressways.However,the terrain in this area is undulating and geological disasters occur frequently,which directly or indirectly endangers the construction and operation of expressway projects.Therefore,it has become the primary task to carry out research on geological disasters along the route in the early stage of expressway construction.In this paper,the geological structure along the Panzhihua-Yanyuan expressway is complex,and geological disasters such as landslides,collapses,and debris flows occur frequently.Carrying out the assessment of the susceptibility of geological disasters along the expressway is of great significance to the site selection,construction and prevention of geological disasters.Based on the identification of the natural conditions and the status of geological disasters along the Pan-Yan expressway,this paper uses remote sensing and geographic information technology to build a geological disaster susceptibility assessment index system.And three models are used to evaluate the susceptibility of geological disasters along the expressway,and the optimal model of geological disasters susceptibility evaluation is obtained through comparative analysis.The main research contents and research results of this article are as follows:(1)Constructed a spatial database of geological environment along the Pan-Yan expressway.It includes collecting and collating relevant data of topography and geomorphology,meteorology and hydrology,geological structure,human engineering activities in the study area.Through remote sensing interpretation combined with field investigation to determine 72 landslides,21 collapses and 27 debris flows in the study area.(2)Establish the evaluation index system for the susceptibility of geological disasters in the study area.Based on the analysis of the geological environment background and the formation conditions of geological disasters in the study area,select 12 factors: elevation,slope,aspect,degree of relief,Terrain Wetness Index,rainfall,distance from road,distance from water system,distance from fault,lithotope,soil type and land use type to constitute geological disasters susceptibility evaluation index system.At the same time,the distribution characteristics of geological disasters in various indicators are counted,and use the Certainty Factor method to find the geological disaster sensitivity category of each index.(3)Use three models to carry out geological disasters susceptibility assessment.Use separate information value(IV)model,Information Value coupled Logistic Regression(IV-LR)model considering the contribution weight of each factor,Information Value coupled Support Vector Machines(IV-SVM)model widely used in small sample research are used The zoning evaluation of the susceptibility of geological disasters is carried out in the areas along the Pan-Yan expressway.(4)Carry out analysis on the evaluation accuracy of different models.Research shows that the prediction results of the three models have high accuracy.The area under the ROC curve corresponding to the IV-SVM model is 0.8401,with the highest accuracy.Therefore,this paper uses the optimal IV-SVM model evaluation results combined with the line mileage to analyze the susceptibility of geological disasters along the line in sections.The evaluation results show that the areas with high,medium,low and unprone areas in the study area account for 19.58%,30.84%,24.22%,and 25.36% of the total area,respectively.