李星, 王红雨, 柴鹏翔, 等. 2023. 淤泥-新填土接触界面渐进剪切破坏微观分析[J]. 工程地质学报, 31(1): 78-89. doi: 10.13544/j.cnki.jeg.2020-389.
    引用本文: 李星, 王红雨, 柴鹏翔, 等. 2023. 淤泥-新填土接触界面渐进剪切破坏微观分析[J]. 工程地质学报, 31(1): 78-89. doi: 10.13544/j.cnki.jeg.2020-389.
    Li Xing, Wang Hongyu, Chai Pengxiang, et al. 2023. Microanalysis of progressive shear failure on contact interface of silt and new fill[J]. Journal of Engineering Geology, 31(1): 78-89. doi: 10.13544/j.cnki.jeg.2020-389.
    Citation: Li Xing, Wang Hongyu, Chai Pengxiang, et al. 2023. Microanalysis of progressive shear failure on contact interface of silt and new fill[J]. Journal of Engineering Geology, 31(1): 78-89. doi: 10.13544/j.cnki.jeg.2020-389.

    淤泥-新填土接触界面渐进剪切破坏微观分析

    MICROANALYSIS OF PROGRESSIVE SHEAR FAILURE ON CONTACT INTERFACE OF SILT AND NEW FILL

    • 摘要: 坝前淤泥面加坝中淤泥坝基和新填筑坝体的接触界面是整个加坝体的薄弱部位,为了进一步探究不同工况下接触界面渐进剪切破坏特性,以宁夏南部山区西吉县南川水库坝前淤泥面加坝工程为研究对象,在改进常规应变式直剪仪的基础上,利用电镜扫描技术,通过控制剪切位移增量的方式对接触界面渐进剪切进行了微观试验研究,并且基于逐步回归分析法获得了影响接触界面强度参数的微结构显著性变量,建立了反映两者关联性的回归方程,研究表明:不同压实状态的淤泥土造成的界面颗粒胶结和结构的改变,是影响界面抗剪强度增加的主要原因,存在一个界面“最优黏结”状态;随着剪切位移增加,界面土颗粒从独立分布的单粒结构的接触形式,逐渐发育成以面-面、边-面接触定向排列的薄片状结构,最终形成不易压缩的块状粒团结构;界面孔隙微结构参数变化规律与宏观黏聚力、内摩擦角变化具有相关性。研究结果可以为坝前淤泥面加坝工程的设计与施工提供参考依据。

       

      Abstract: The contact surface of the silt soil and the new fill in the raising earth dam from upstream is the weak part of the whole dam body. This paper studied the progressive shear failure characteristics of the contact interface under different working conditions. It took the raising earth dam project from upstream deposited mud in Nanchuan Reservoir, Xiji County, the southern mountainous area of Ningxia, China as the research object. On the basis of improving the conventional strain-type direct shear instrument, using the electron microscope scanning technology, the microscopic analysis of the progressive shear of the contact interface was explained by controlling the shear displacement increment. Finally, the stepwise regression analysis method was used to obtain the significant variable of the micro-structure that affected the strength of the contact interface. Their regression equation was established. The results show that the silt soil in different compaction states causes interface particle cementation and structural changes, which is the main reason for increasing the interface shear strength. There is an interface "optimal adhesion" state. Meanwhile, with the increase of shear displacement, the interfacial soil particles are gradually developed into a flaky structure arranged in face-to-face and edge-to-face contact orientation from the independently distributed single-grain structure contact form. Finally they formed an incompressible block shaped pellet structure. And the change law of interface pore micro-structure parameters is related to the change of macroscopic cohesion and internal friction angle. Therefore, the results of this study can provide a certain reference for the construction of silt surface dam.

       

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