| Jiaocheng County of Shanxi Province is located in the Loess Plateau with complex geological environment,developed fracture structure,poor integrity of the rock mass and widely distributed unconsolidated formation.Simultaneously,Jiaocheng County possesses abundant mineral resources,along with frequent human activities,causing a high degree of mine development and the area of underground goaf is 13.98km~2.In recent years,due to the fragile geological environment of Jiaocheng County and frequently occurring geological disasters,the local social and economic development have been affected to a certain extent,also the safety of life and property of locals have been put in jeopardy.Therefore,it is of a great practical significance to identify the current situation of geological environment and geological disasters in Jiaocheng County and evaluate the risk of geological disasters in Jiaocheng County.A geological disaster risk assessment system is established based on the geological environment frangibility and the risk of current status of geological disasters after analyzing the geological environment conditions and the development characteristics of geological disasters in Jiaocheng County.By considering two aspects that causes disasters,the basic environment condition and the direct cause for disasters,there are 10 factors chosen and applied as evaluation index for geological environment vulnerability,rock and soil structure,slope of the terrain,river system,vegetation coverage,hydrogeological conditions,human project activities,goaf distribution,rainfall,fault zone activities and population density.According to the present development characteristics of the disaster sites,3 factors including the distribution density,stability and disaster situation of the disaster sites are selected as the evaluation index of geological disaster risk.The ArcGIS platform is used to divide the county region into grids,the catastrophe theory in combination with the Jenks optimism is utilized to calculate the weights of each index;After the grid superposition and calculation,the vulnerability and risk index of the evaluation unit are obtained.The risk evaluation method and the risk evaluation matrix method based on the catastrophe theory are selected respectively,the results of vulnerability and risk assessment are added and calculated to obtain the risk evaluation results of geological disasters in Jiaocheng County.At last,by natural discontinuity point method,the county region is divided into 5 levels presenting high-risk area,higher-risk area,medium-risk area,lower-risk area and the low-risk area occupying areas of 22.44km~2,96.05km~2,400.40km~2,713.56km~2 and 593.95km~2 respectively,taking up 1.23%,5.26%,21.92%,39.07%and 32.52%respectively of the whole county.On the basis of the distribution of different geological disaster sites and geological environment conditions,the high-risk areas are further divided into 8 sub-areas in accordance with disaster categories,along with the higher-risk areas being divided into 8 sub-areas.There are in total 61 geological disaster sites in the high-risk area,including 11 landslides,8collapses,9 unstable slopes,4 debris flow,22 surface subsidence and 7 ground fissures.In addition,there are in all 25 disaster points in the higher-risk areas,covering 6 landslides,4collapses,4 unstable slopes,4 debris flow and 7 surface subsidence.The evaluation results are verified by the success rate curve method and are proven to be mainly in accordance with the actual conditions of Jiaocheng County.Therefore,the risk evaluation system can be provided as the reference for the planning of economic development of Jiaocheng County. |
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