Evaluation Of 3D Slope Stability Based On Slope Units In Mountainous Region

Due to the complicated engineering geographic and geomorphic conditions and the frequent natural geologic hazards in western mountainous region, before the construction planning and site selecting, we should investigate and evaluate the geological hazards development of the whole study area, in order to avoid building in the area where geological hazards is likely to happen, it is of important significance for the life and property safety of people in mountain areas. Nowadays, however, most geologic hazard(landslide hazard mainly) evaluation is qualitative or partly quantitative, selecting several impact factors of geologic hazard to build the index system, then based on the quantitative classification and some other approaches, use mathematical models to do the comprehensive evaluation, and get the results. In these evaluation processes, there are many qualitative approaches, so these evaluations have no unified standards, also have some defects, such as the selection of index factors, the quantitative classification and uncertainty of each index factors.Supported by the task of "twelfth five-year" national science and technology support plan “Town regional spatial planning and land use optimization technology integration demonstration”(2012BAJ22B06).Choosing Yihe town, Fuling district, Chongqing city as the study object, this paper has mainly studied how to do the quantitative evaluation of soil slopes and rock slopes in mountain areas with slope units partition method, 3D slip surface searching method, artificial intelligence algorithm, 3D limit equilibrium method and reliability theory based on GIS, thus to make up the shortage of qualitative evaluations, and to provide a more scientific and reliable basis for the development of western mountainous area. The main work and results of this paper is as follow:(1) Supported by GIS, this papar classify the evaluation units and build the data sets for the slope stability evaluation, including to divide the whole study area into several independent study objects based on the slope units partition method, and the establishment of slope units data sets, which storing the geological spatial information and the geomechanical parameters of each slope unit in the form of points.(2) Use the slope units data sets to evaluate the soil slope stability. Based on 3D limit equilibrium method, 3D slip surface searching method and reliability theory, conclude a set of method which can calculate the stability factors of every soil slopes of the whole study area, automaticly search the most dangerous sliding plan, calculate reliability, and do the stability evaluation.(3) Use the slope units data sets to evaluate the rock slope stability, which deformation and destruction is mainly dominated by structural plane. Based on 3D limit equilibrium method, reliability theory, and a new method of dangerous structure plane searching, conclude a set of method which can calculate the stability factors of every rock slopes of the whole study area, automatic search the most dangerous sliding rock mass, calculate reliability, and do the stability evaluation.(4) Apply the quantitative slope stability evaluation method to engineering, this paper selects a 6 square kilometers area in Yihe town, Fuling district, Chongqing, use the quantitative evaluation method of slope stability to establish the slope units data sets, analysis the soil slope and rock slope stability of whole study area, finally according to the stability factors and probability of failure to get the slope stability evaluate results of the whole study area, by comparision, the results is consistent with the reality.