关键词: 黄土滑坡, 稳定性分析, GIS

Abstract:

Landslide is one of the most damaging natural hazards in China, thus landslide susceptibility mapping plays an important role in disaster prevention. Probability-based analysis is the most popular method to evaluate a wide range of natural slope instability risk. But the applications of it are limiting factor for lack of landslides data. In order to evaluate a wide range of natural slope instability risk effectively and quantitatively, this article presents a new method which evaluate regional slope instability risk, combining with two-dimensional mechanical analysis model and Geographic Information System (GIS) method. Firstly, a region is divided into a group of slope zones according to the terrain condition by using watershed hydrology analysis method in GIS. The location of main section line of each slope zone is set according to its average slope inclination and angle. A series of possible sliding surfaces are formed and the minimum safety factor of every slope zone is calculated based on two-dimensional mechanical analysis model. On the basis of calculation results, slope risk zoning map is drawn. A loess gully region in Jintai District of Baoji City, Shaanxi Province, China, is selected as the study area. The proposed method is verified. First of all, the topographic map is changed into a digital elevation model, with the planar range is 3 km×4 km and grid size is 10 m. According to the process mentioned above, the area is divided into 76 zones using hydrology tools. Secondly, the grid layers of strata interfaces are interpolated with the data of stratums, which is obtained from drilling and investigation. And then, geologic model of this area is set up using multi grid layers method. Thirdly, a regional stability evaluation program is developed according to the stability factor of each unit. It can read files in GIS formats, extract sections automatically, access stability, and convert the results into GIS data. Finally, with this program, calculation profile of every zone is generated automatically and the minimum safety factor of every profile is figured out by using 2D Bishop simplified method. The coefficients of the zones are sorted into four groups. According to the groups, regional slope risk zoning map is drawn. The method proposed in this paper is based on two-dimensional limit equilibrium method, which is the most commonly used in engineering. It can obtain not only the distribution map of safety coefficient, but also the scale and location of most dangerous slip surface. The method and program are used in seismic geological disasters assessment in Baoji City, and good results have been obtained. This study provides a new way to evaluate natural slope risk of large area.

Key words: loess landslide, stability analysis, GIS