Risk Assessment Of Geological Hazards In Baoding Section Of Rongwu Expressway

Based on the comprehensive analysis of previous data and research results,the field survey of geological disasters was carried out in the area of 20 km on both sides of rongcheng(cheng-wuhai)expressway(baoding section).Two typical landslides in the research area,the north landslide of qianyilin village,yinfang town,laiyuan,and the east landslide of ganhejing village,ganhejing township,yixian county,are sampled.The phase analysis is carried out by X-ray diffraction method,and the semi-quantitative analysis of clay minerals is completed by using the K value method.The compositions and relative contents of the materials at the corresponding positions in the two landslides were determined and it was considered that clay minerals played an important role in the initiation of landslides.According to the collected data and field survey results,"slope","slope height","human engineering activities","geological structure","engineering rock formation","rainfall","vegetation","river" and "peak acceleration of ground motion" are selected as influencing factors on the basis of ArcGIS platform to form a spatial geographic database.Based on the principle of minimum relative information entropy,the objective weight determined by entropy method and the subjective weight determined by ahp are fused,and the non-quantization method of "centralization" is used to eliminate the difference in order of magnitude and dimension of each index,and then a linear comprehensive evaluation model is established.Based on this model,the risk assessment of geological disasters was carried out in the research area.By comparing the assessment results with the actual disasters,it was found that 97.3% of the known geological disaster sites fell in the high and medium risk areas,which verified the rationality of the model and provided the basic basis for the risk management of geological disasters.Through the analysis of the evaluation results,the following conclusions can be drawn :(1)in the study area,the high risk areas of landslides are mainly concentrated in the western mountainous areas,and the risk degree is higher in the west and lower in the east.The main control factors are slope,human engineering activities,slopeheight and engineering rocks.(2)in terms of geological disaster prevention and control,this paper believes that the landslide treatment in the study area should follow the principle of drainage and waterproofing.For the prevention of collapse,the excavation face can be improved into multi-stage platform to limit the collapse path.The prevention and control of debris flow disaster can be carried out by "blocking,draining and guiding" in combination with biological engineering and water diversion.(3)based on the risk assessment of individual disasters,it is found that the collapse in the study area can be divided into sliding type(four),toppling type(one)and falling type(one)according to the form of motion.Most alluvial fans formed by debris flow are in the state of lower cut,which is a declining period.(4)the sliding zone belongs to the rich clay mineral area,and it is considered that the landslides in the study area are mostly distributed in gneissein-exposed area,which is closely related to clay minerals,the weathering products of silicate minerals.