Study On The Hazard Zonation Of The Ground Fissure In Guanzhong Basin

Ground fissure, a kind of ground line geological disaster, is the deformation and fracture of the stratum, which is formed under the combination of internal and external geologic stress. Located between the ordos plateau and the Qinling orogenic belt, Weihe fault basin of Guanzhong area is one of the most development area of the ground fissure disasters in our country. Now there are 177 disaster points and a total of 264 ground fissures are found. These ground fissures do serious damage to the Guanzhong basin urban planning, land use and construction of major projects.This paper is based on the China Geological Survey’s geological survey project " geological environment suitability assessment of Guanzhong urban agglomeration city constuction ". By means of field investigation, exploration, comprehensive analysis, existing geology and hydrogeology data, we have ascertained the fissures’ occurrence background, distribution, development characteristics and its influencing factors in the Guanzhong basin. These research results enable us to conform and analyse the genetic type of the ground fissures and its reasons for the formation of typical ground fissures. Based on the methods of analytic hierarchy process(AHP) and information values, we have established an evaluation index system of ground fissure risk, which includes the geomorphic types, formation lithology, landform boundary zone, geological structure, earthquake factors, groundwater changes, ground subsidence, collapsibility loess, annual average rainfall, crack size, the distance from the ground fissure and ground fissures’ density distribution.We also ascertain each index weight and extract each index of ground fissure disasters’ information values. Using spatial analysis function of mapgis and building the ground fissure disasters risk assessment model of AHP- information values, we conduct the Guanzhong basin ground fissure disaster’ risk zoning assessment, then we divide the risk of ground fissures in the study area into large level, medium level and small level. Combining with genetic type and zone width of surface,we has established the suitability evaluation standard of Guanzhong basin urban construction, and separate ground fissure area into different suitable construction zone such as inappropriate suitability, poor suitability, asic suitability and appropriate suitability.By ascertaining the ground fissures’ development status quo of Guanzhong basin, we have conducted ground fissure disaster’s risk zoning and ground fissures’ suitability evaluation of town construction. These provide information support and scientific decision-making evidence for urban planning and construction of Guanzhong basin and also for comprehensive prevention and reduction of fissure disasters.