Research On Risk Zoning Of Ground Fissures In Big Xi’an Area

Big Xi ’an area is located in the central of Weihe fault depression basin in Guanzhong plains. The basement structure is complex and the fault activity is strong. Big Xi ’an area is one of the most serious regions in the development of the ground fissure disasters in our country. Along with the development of the western region, the Silk Road Economic Belt and other national strategies planning and implementation, the scientific planning and coordinated development of big Xi’an city construction has risen to an unprecedented levels. Therefore, it is of great importance to carry out the risk zoning of ground fissures in this area.In dissertation, based on the existing various foundation, hydrology, disaster, engineering geological data, using ground investigation and mapping, drilling, trenching, methods of geographic information system analysis, combined with field survey results, we summarize the distribution law, activity characteristic and the destructive effect of features in the big Xi’an area. The evaluation index system is established by using the analytic hierarchy process(AHP) through selecting 13 factors such as the terrain and landform, the type of rock and soil, the activity of fault, the density of ground fissures, the activity of ground fissures and so on. We need to seize the essence that the non-uniform deformation of the shallow soil layer caused the occurrence of ground fissures. When the evaluation index of the big Xi ’an ground fissures risk zoning was selected and quantified, surrounding the non-uniform deformation of geological environment and conditions, we should introduce the dominant idea of "differentiation thinking". Based on MapGIS software platform, the big Xi ’an ground fissures risk zoning map is obtained by superimposing the geological project layer. The results of the risk zoning show that the high risk area of ground fissures in big Xi ’an region covers an area of 2388.56km2, occupying the whole area of 15.74%. The dangerous area covers an area of 7988.21km2, occupying the whole area of 52.63%. Low risk area covers an area of 4801.13km2, occupying the whole area of 31.63%. On the basis of the big Xi ’an ground fissures risk zoning, according to the differences of the adaptability to the geological environment for the different structures and the different functions of the buildings(structure), we put forward the rational distribution of Xi ’an city construction planning, and provide the scientific basis and important reference for the regional planning and government decision-making.