The Research On Deformation Of High Slope Stability Under Unloading Stress Environment

The thesis takes bank slope on the dam area of Baihetan Hydroelectric Power Station as an illustration. Based on extensive field investigation and interior analysis, combining with Hydrogeology and Engineering Geology condition and the field deformation of high slope,the author uses theoretic and numerical analysis and so on tests to assist his research. The main results of this paper can be summed up as follows:1.The main landform characteristics of research area is medium-hill valley landscapes by long-term weathering and cutting of flowing water, which low left-steep right, wider at the top of the typical "V" valley. Cutting action under the strong small-scale collapse of the slope provides the necessary potential energy accumulation and free surface. In addition, the side etching effect exacerbates the slope collapse. Steep-dip slope topography lay the foundations of the formation of landslide.2. The deformation mechanism of right bank slope are mainly progressive collapse; collapse instability control by basalt layered structure, conjugate shear fracture, unloading cracks and columnar joints and other structural surface.3. The stability analysis of steep bank slope associated control by angle Fault 18 and low-angle fault zone between layers found that the side slope obviously control by weak structural surface. The total displacement of rock slope along the tuff layers gently inclined fault zone and the steep-dip slip fault zone of the crack, is typical slip-crack model.4. The results of 3D slope stability analysis show that:the x direction displacement of layer fault zone where the relative density higher than the relatively low-rise areas, and exists a critical depth, If the vertical depth goes beyond the critical depth,the same depth plane displacement will be no longer parallel to the unloading zone boundary surface; the y opposite direction displacement control by its height, the displacement mainly from overlie rocks of the interlayer fractured belt; the total displacement mainly tend to the displacement of interlayer fractured belt; the concentrated stress area exist in the north (south) boundary region and the toe of study area. 5.The slope deformation destroying phenomenon in the dam area of Baihetan hydropower station are the unloading dynamic-relaxing rock mass formed by epigenetic deformation and landslide that controlled by low-angle structural plane and steep-dip structural plane, which is dominated by creeping slip and tensile cracking. The slope deformation destroying will be dominated by block sliding, decomposition and avalanche, the stability of whole sliding is good.