Risk Assessment Of Geological Hazards In Xuanhan County

Based on the investigation of the Geological Hazard Investigation Project of the River Basin in the East Sichuan Basin,this paper analyzes the deformation and failure characteristics and mechanism of different types of slopes in the county,based on the investigation of the geological environment conditions and geological hazard development characteristics of the Xuanhan County,combined with the analysis of typical geological disasters.Based on the general situation of the county's urban geological disasters,combined with the actual situation of the county,the appropriate impact factors were selected,and the fuzzy comprehensive evaluation and the hierarchical entropy variable weight method were adopted.Based on the ArcGIS platform,the risk of the study area was obtained.Partition map.Through the comparison of the results of different evaluation models,the risk assessment of the geological disasters in Xuanhan County was comprehensively evaluated,and the following main research results were obtained.(1)Analyze the geological environment conditions of Xuanhan County by collecting relevant geological data and field investigations in Xuanhan County and its periphery.According to the topography,slope geology type,stratum lithology combination and actual engineering construction,the county is divided into six engineering geological divisions,and the failure mode and stability of the slope are preliminarily judged.(2)Based on the survey of topography,stratigraphic lithology and slope structure of Xuanhan County and surrounding peripheral survey areas,according to the type of slope structure,the slope body is divided into forward slope,reverse slope and horizontal-sloping slope.According to the lithological combination,the slope structure types are further divided,and the stability factors and deformation failure modes of various slopes are analyzed.Combined with 40 typical disaster points,the investigation analyzes the development law of geological disasters in urban areas.(3)By analyzing the development characteristics and basic influencing factors of geological disasters in Xuanhan County and the surrounding investigation area,summarizing the general laws,and combining the slope failure mode of Xuanhan County and the future development direction of the town,select the slope,elevation and stratigraphic group.Establishing six evaluation factors from the water system distance,the distance from the highway and the slope structure,and establishing a risk assessment index system for the geological disasters in Xuanhan County.On this basis,the evaluation factors are quantified,and the analytic hierarchy process is used to determine the weight of each factor.(4)Using the hierarchical fuzzy comprehensive evaluation method and the hierarchical entropy variable weight method to carry out the risk assessment of Xuanhan County,and obtain the danger map of geological disasters.Two different models divide the study into three risk zones,and the results of the comparative analysis of the evaluation methods show that:The low-risk area obtained by the hierarchical fuzzy comprehensive evaluation method is 16.47km~2,accounting for 37.4%of the total area of the county;the medium-risk area is 25.24km~2,accounting for 57.4%of the total area;the high-risk area is 2.29km~2,accounting for 5.2%of the total area.The low-risk area of geological disasters obtained by the hierarchical entropy variable weight method is 24.51km~2,accounting for 55.7%of the total area;the area of dangerous areas in geological disasters is 17.38km~2,accounting for 39.6%of the total area;the area of high-risk area is 2.11km~2,accounting for the total area.4.8%.Two different risk assessment models can reflect the dangerous sub-area of the county.The results of the evaluation of the high-risk areas of geological disasters are basically the same,and the main low-risk and medium-risk differences are large.The hierarchical entropy variable weight method can synthesize the opinions of experts,and can also reduce the influence of subjective factors in combination with the actual situation.Therefore,the obtained risk zoning results are more accurate and have reference value for future urban development.