The Research On The Stability Of Low-grade Metamorphic Rock Weathered Layer Slope

Along with the development of china's economy and the faster pace of high-grade highway construction in mountainous areas, a large number of highways which are constructing or will be constructed, inevitably to pass through the adverse geological conditions, in addition most west areas are hills and mountainous, the depth of stratum weathering is big, the overburden layer is thick, the rock structure is stave,so it will certainly meet a lot of slope problems. In recent years, the development of highway was rapid in GUIZHOU, but also met a series of engineering technology questions. Because the terrain landform is very complex, the mountain ridge is rugged, and the gully is world-wide,there are a lot of landslide problems due to the instability of low-grade metamorphic rock weathered layer .They brought great loss to the highway construction, and brought a serious threat to people's personal safety and property.This paper takes the section of JK104+840～SK104+840 in SANSUI-KAILI highway for example. Based on the the collection of existing exploration data, design information and field investigation of more than one hundred slopes along the sansui-kaili highway ,and on the basis of comprehensive knowledge , the slope were classified,and the type of low-grade metamorphic rock weathered layer slope are divided, the characteristics of low-grade metamorphic rock weathered layer slope are summarized .and the types of damage of low-grade metamorphic rock weathered layer slope are summarized in detail.with the engineering example of low-grade metamorphic rock weathered layer slope in SANKAI highway, the major influence fators of stability are explored and the impacts of weathering on slope stability are analysed.This paper describes the constitutive relations models of rock, the yield criterion of rock, the basic principles and the calculation process of elastic-plastic finite element , the conversion of yield criterion in detail, and it explores the Slope Instability basis and the method of determining the Safety coefficient, which is based on the theory of strength reduction of the elastic-plastic finite element. It describes the basic principles and the calculation process of imbalanced thrust force method(the transmitting coefficients method)which Belong to the limit equilibrium method. On this basis, the decline of the regional geological environment for the conduct of the research are analysed , including topography, lithology, structural geology, hydrogeology and meteorological characteristics, and the project characteristics of weathered rocks of low-grade metamorphic rock weathered layer slope are summaried. It discusses the formation mechanism of low-grade metamorphic rock weathered layer slope and analyzes the deformation and failure model .it uses the transmitting coefficients method and the elastic-plastic finite element strength reduction method to calculate the slope stability, the project example shows that the elastic-plastic finite element strength reduction method to calculate low-grade metamorphic rock weathered layer slope stability is feasible. According to the results of ow-grade metamorphic rock weathered layer slope and its deformation and failure characteristics ,it gives the corresponding control measures and treatment measures.Therefore, this paper to the characteristics of low-grade metamorphic rock weathered layer slope, the deformation and failure mechanisms, the analysis and evaluation of stability, and the rational control measures, such as the issue of the study, not only of important theoretical value, but also regarding GUIZHOU province and even the national low-grade metamorphic rock weathered areas, it also has a certain reference value and guiding sense for the engineering geological survey of slope,the evaluation of slope stability and the design and treatment etc.