滑坡碎屑流冲击导引结构的冲击机理和堆积特征研究

    IMPACT MECHANISM AND ACCUMULATION CHARACTERISTICS OF LANDSLIDE DEBRIS FLOW IMPACT GUIDING STRUCTURE

    • 摘要: 导引结构可将碎屑流引流到偏离山区建筑或工程布置分布的区域,以防范滑坡碎屑流灾害。为探究导引结构对滑坡碎屑流运动和堆积特征的影响,基于离散元方法,分析导引角度、颗粒级配和导引宽度对死区形态特征、冲击力分布和下游堆积特征的影响。结果表明:导引角度的变化对死区形态变化影响显著,颗粒级配和导引宽度对死区形态影响较小。随着导引角度增大,中粗颗粒含量的增加会增大流动层颗粒在冲击面上的占比,导致绕流颗粒的抛射角和扩散角增大,导引结构下部位置的死区颗粒间易出现强力链集中现象,而导引宽度的增加则导致绕流颗粒抛射角和扩散角差值的减小,致使碎屑流产生相对更集中的运动。流动层颗粒的占比控制着冲击力曲线的波动性和动态冲击阶段导引结构上部的冲击力峰值,死区颗粒的占比控制着冲击力曲线的稳定性和整个冲击过程中导引结构下部的冲击力峰值。绕流颗粒抛射角越大,堆积体的堆积长度、面积和最大厚度越大,堆积宽度越小。研究结果可为滑坡碎屑流防治工程结构设计提供参考。

       

      Abstract: The guiding structure can divert landslide-induced debris flows away from mountainous buildings or engineering layout areas. To investigate the influence of guiding structures on the movement and accumulation characteristics of landslide debris flows, this study employed the discrete element method to analyze the effects of guiding angle, particle gradation, and guiding width on the accumulation pattern in the dead zone, the distribution of impact forces, and overall deposition features. The following conclusions are drawn: variations in the guiding angle significantly affect the accumulation pattern in the dead zone, whereas particle gradation and guiding width have only minor influences. As the guiding angle increases, a higher proportion of medium and coarse particles enhances the flow of particles on the impact surface, leading to increased throwing and diffusion angles of bypassing particles; strong force chains become mainly concentrated at the lower part of the guiding structure. In contrast, an increase in guiding width reduces the difference between the throwing angle and diffusion angle of bypassing particles, resulting in a more concentrated movement of the landslide debris flow. Flowing particles govern the fluctuation of the impact force curve and the peak impact force on the upper part of the guiding structure during the dynamic impact stage, while particles in the dead zone control the stability of the impact force curve and the peak impact force on the lower part throughout the entire impact process. A larger throwing angle of bypassing particles corresponds to greater accumulation length, accumulation area, and maximum deposit thickness, but a smaller accumulation width. These simulations provide insights of scientific value for designing control structures for landslide debris flows.

       

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