The Risk Assessment Of Mountain Collapse In Huaibei-Yanqi Of Beijing

Collapse is a common type of geological hazards occurring in mountainous areas,and often due to its scale is large or small and the macro feature is not obvious,resulted in it is more threatening. Heavy rainfall in Beijing city in July 2012, triggered a number of collapses, and resulted in a large number of houses and road damage.With the vigorous development of tourism in the suburbs of Beijing, the construction of the road and the inappropriate development of the scenic area, a lot of artificial slopes are formed, which is the condition for the occurrence of the collapse, and forming the potential threat.The paper is relying on the project that the detailed investigation of Beijing geological disasters, on the basis of field collapse disasters detailed investigation and data analysis, using ArcGIS and combinating the two kinds of mathematical methods,to study the collapse hazard zonation and evaluation for Huaibei-Yanqi of Beijing.The main research results are as follow:(1) Establish the evaluation system of the collapse risk in the study area. On the based of analysising the formation conditions and inducing factors of collapse in the study area, the eight principal factors of collapse are selected, respectively elevation,undulating topography, slope degree, aspect, formation lithology, cleavage fracture degree, average annual rainfall, human activity intensity; and the eight factors are quantified and classified.(2) Use ArcGIS and combine the fuzzy comprehensive evaluation method to study the collapse hazard zonation and evaluation of the study area. Use MATLAB to calculate the membership degree of each unit of each factor, multiplied by the the weight obtained by AHP, and obtain the maximum membership degree of each grid cell. Combine fuzzy comprehensive evaluation and GIS to get the collapse risk zonation of the study area and evaluate the results of zonation.(3) Use ArcGIS and combine the information quantity method to study the collapse hazard zonation and evaluation of the study area. Through the classification function of GIS, the 8 factors are divided into 27 grades, the information value of each grade is obtained. Combine information quantity method and GIS to get the collapse risk zonation of the study area and evaluate the results of zonation.(4) Compare the evaluation results of two kinds of mathematical models. The most of the actual survey points of collapse fall in the middle and high danger zone,qualitative description, the zonation results of the two models are consistent with the actual situation. The AUC curve tests of two models are "convex". The calculation shows that good result in the evaluation of the two models, quantitative description,the evaluation results of the two models are good. The AUC value of the information quantity method is larger than the value of the fuzzy, and the evaluation result of the information quantity method is more accurate than the fuzzy comprehensive evaluation method.