| As the vigorously development of economic construction in China,geological environment problems are becoming more and more serious,and geological disasters has been occurring from time to time.In order to make human and nature can coexist harmoniously and maintain the sustainable development of the city,it’s of great significance to study the characteristics and risk evaluation of geological hazards.In this paper,Zichang city is taken as the research area,which is located in the northern of Shaanxi province.The characteristics of regional geological hazards are analyzed from the aspects of topography,geological environment,ecological environment and human engineering activities.The stability and instability movement characteristics of typical landslides in the region are analyzed based on limit equilibrium method and strength reduction method.Nine types of evaluation factors,including slope,rock and soil mass type,land use type,normalized difference vegetation index and average annual rainfall,were selected to construct risk evaluation indexes.The results of regional risk zoning were obtained by comparing and analyzing the three methods:traditional information volume model,combined weight model and machine learning model.Four evaluation factors,including population,road,farmland and GDP,were selected to evaluate the vulnerability of geological disasters in Zichang city by using the combination method of analytic hierarchy process and Fuzzy comprehensive evaluation method.Finally,according to above results,the risk assessment in Zichang city was completed.The main achievements of this paper are as follows:(1)There are 105 geological disasters including collapses and landslides in Zichang city.They are mainly distributed in the areas along the rivers,where the loess thickness is large and human engineering activities are intense.The thick loess cover and broken topography in the region provide favorable topographic and geomorphic conditions for the development and formation of geological disasters,while the concentrated rainfall and the intensity of human engineering activities are the main reasons for the occurrence of geological disasters.(2)According to the landslide survey report,xinzhai river village landslide stability is studied,and based on limit equilibrium method and strength subtraction in FLAC3D,three sections on landslide evaluation model is established,The stability of the landslide is analyzed under two conditions and the result shows that the stability of this landslide is worse with heavy rainfall.As a whole,the landslide is a sliding form of creep-pull-crack deformation.(3)Through the information model,the introduction of distance function combination empowerment model with genetic algorithm optimization support vector machine model of three kinds of methods for long,made an evaluation of the geological disaster risk,and by using ROC curve accuracy test of three kinds of evaluation results,it shows that machine learning model can better deal with the nonlinear relation between evaluation factors.The risk assessment results can be also more accurate than others.(4)The vulnerability assessment of Zichang city was completed based on fuzzy comprehension evaluation method and analytic hierarchy process models,and then according to the formulas of "Risk=Hazard X Vulnerability",we can get the geological disaster risk assessment result.The extremely high and high risk districts(8.56%)are focus in the central of Zichang city;the medium risk area(17.89%)are mainly distributed along the rivers and roads;low and very low risk areas accounted for 73.55%,mainly distributed in the northwest of Zichang city. |
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