| The survey area is located in the south of Wuyi Mountain.Because of the special geological environment conditions,human engineering activities,rainfall and other factors,there are geological disasters such as mountain collapse,landslide and debris flow in the region.Among them,the landslide is the most serious,which has caused a great degree of negative effects on the social and economic development of Shaxian County.Based on the project "1:50,000 Landslide Geological Disaster Risk Investigation and Evaluation of Shaxian District,Sanming City",conducted by Geological Brigade 196 of Fujian Province,this thesis summarized and sorted out the relevant geological data within the region,and also analyzed and studied the data of landslide geological disasters.Based on this,the natural conditions and geological environment of the region were explored,and the types of geological disasters were sorted out.The development characteristics of all kinds of geological hazards are expounded,and the distribution law of these geological hazards is explained.In the research process,GIS technology,comprehensive index model and logistic regression model are used to evaluate and analyze the risk degree of landslide geological disaster in this area.And the basic results are as follows:(1)Research shows that 151 geological disasters have occurred in Shaxian County,including mountain collapse,landslide and debris flow.There were 86 landslides alone,accounting for 56.95% of the total.The types of landslide mainly include soil,small,shallow,gradient and traction.(2)The basic pregnancy and disaster conditions in the region are explained in detail.The following influencing conditions are selected,including landform,structure,slope structure type,slope engineering geological conditions,hydrology,human engineering activities,etc.,to elaborate the basic disaster occurrence conditions in the region.The main control factors and laws which affect the breeding of geological disasters are as follows: landform,geological structure,engineering geological rock group,etc.The degree of disaster occurrence is also divided into four levels of geological conditions,including extremely high,medium and low hazard geological conditions.(3)The generation mechanism of geological landslide disaster in Shaxian area is explained,and the failure mode of landslide is obtained.According to the case study,the author points out that the mechanism of landslide can be divided into two modes:the sliding of soil along the internal clipping failure surface and the deformation failure caused by the sliding of soil along the soil-rock interface.In addition,the failure modes are also divided into two types: creep slip-pull cracking type and slip-pull cracking type.Here,the slip-pull cracking mode is further divided into two types,namely,the slip type of soil-rock contact surface and the forward slip type of weak basement.(4)Six evaluation factors,including slope,curvature,elevation difference,engineering geological strata,overburden thickness and fracture distance,were selected for the general study area during the whole study process;Eight evaluation factors were selected for those key study areas,including slope grade,elevation difference,slope shape,overburden thickness,engineering geological structure,slope structure,fracture distance and cut slope height.The evaluation results show that those common research areas are mainly low-risk areas,accounting for 84.77% of the total.Under the premise of rare rainfall in 10 years,the high risk area reached 12.77 square kilometers,accounting for 11.58 percent of the total area of the region.The high-risk area reached 25.58 square kilometers,accounting for 23.19 percent of the total area.The risk reached 23.42 square kilometers,accounting for 22.06% of the whole area;The low-risk area reached 47.60 square kilometers,accounting for 43.17 percent of the total area. |
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