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卸荷环境下高边坡的变形特性研究

The Research on Deformation of High Slope Stability under Unloading Stress Environment

【作者】 姚雷

【导师】 徐则民;

【作者基本信息】 昆明理工大学 , 地质工程, 2011, 硕士

【摘要】 本文以白鹤滩水电站坝址区右岸坡为研究对象,在大量现场调研与室内分析基础上,结合研究区工程地质条件、水文地质条件以及复杂高边坡实际变形破坏模式,采用理论分析和数值模拟等手段,得出的主要结论和研究成果如下:1、研究区地貌发育主要表现为长期风化以及流水下切作用下的中山峡谷地貌景观,发育典型的左缓右陡、上宽下窄的典型“V”形河谷。强烈的下切作用为岸坡孕育小范围崩塌提供了必要的势能累积与临空面,另外,侧蚀作用进一步加剧了岸坡崩塌作用。高陡地貌为右岸坡崩塌奠定了基础。2、右岸岸坡变形破坏模式的主要是渐进性的局部崩塌;崩塌失稳受到玄武岩层状构造、共轭剪切断裂、卸荷裂隙及柱状节理等多种结构面的协同约束作用。3、通过对坝区岸坡在陡倾角断层带F18、缓倾角层间错动带的联合影响下的模拟分析中发现边坡的稳定性受结构面控制作用很明显。边坡岩体的总位移形式表现为沿缓倾角凝灰岩质层间错动带的滑移和沿陡倾角断层破碎带的拉裂,是较为典型的主滑移-次拉裂模式。4、坡体三维数值模拟计算的稳定性分析结果表明:x方向位移量层间错动带相对密集的地方高于相对层数较少的地方,且存在一个临界深度,当垂直埋深超过这一临界深度相同位移量界限面不再平行于卸荷带界限面;y反方向位移主要受其高程控制,位移主要来自层间错动带上覆岩体;总位移主要以沿层间错动带倾向的位移为主;白鹤滩水电站中坝区右岸坡坡面靠近北侧边界区域应力相对集中,在南侧边界以及坡脚部位有应力集中现象。5、白鹤滩水电站坝区岸坡变形破坏方式主要表现为表层的卸荷松动以及缓倾角层间错动带以及陡倾角断层破碎带相组合控制的滑移—拉裂;具有时效变形特点以局部崩塌、分块滑移、解体为主,整体稳定性良好。

【Abstract】 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.

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