郑光, 许强, 彭双麒. 2019: 滑坡-碎屑流的堆积特征及机理分析. 工程地质学报, 27(4): 842-852. DOI: 10.13544/j.cnki.jeg.2018-241
    引用本文: 郑光, 许强, 彭双麒. 2019: 滑坡-碎屑流的堆积特征及机理分析. 工程地质学报, 27(4): 842-852. DOI: 10.13544/j.cnki.jeg.2018-241
    ZHENG Guang, XU Qiang, PENG Shuangqi. 2019: MECHANISM ANALYSIS OF THE ACCUMULATION CHARACTERISTICS OF ROCK AVALANCHE. JOURNAL OF ENGINEERING GEOLOGY, 27(4): 842-852. DOI: 10.13544/j.cnki.jeg.2018-241
    Citation: ZHENG Guang, XU Qiang, PENG Shuangqi. 2019: MECHANISM ANALYSIS OF THE ACCUMULATION CHARACTERISTICS OF ROCK AVALANCHE. JOURNAL OF ENGINEERING GEOLOGY, 27(4): 842-852. DOI: 10.13544/j.cnki.jeg.2018-241

    滑坡-碎屑流的堆积特征及机理分析

    MECHANISM ANALYSIS OF THE ACCUMULATION CHARACTERISTICS OF ROCK AVALANCHE

    • 摘要: 滑坡-碎屑流是一种沿着斜坡表面作远程运动的岩石碎屑流动体。碎屑流体在远程运动过程中会出现粒径分选,并在堆积体中呈现出一定的层序特征。本文通过开展碎屑流滑槽试验,观测了碎屑流运动过程中的粒径分选过程,并重点研究了碎屑流堆积体的垂向和滑移方向层序,采用分层和分段筛分法,对不同粒径的颗粒含量进行了分析,揭示出碎屑流堆积体内部不仅在垂向上具有反粒序结构,还在滑移方向上具有双峰分布形态。这两种堆积特征在6.24茂县新磨村滑坡和8.28纳雍普洒村崩塌堆积体的块石分布规律中得到验证,它们是滑坡-碎屑流体运动过程中块石之间相互作用的宏观反映,是分析碎屑流远程运动机制的重要现场证据。通过室内滑槽试验和实例分析,得到以下结论:碎屑流运动过程中产生的弥散压力和振动筛分是导致碎屑流堆积体中形成垂向反粒序以及滑移方向双峰堆积形态的重要原因。其中振筛作用的动力来源为碎屑流滑移区的不规则起伏引起的碎屑体振荡,以及由粒径差异造成的动量不均衡碰撞。

       

      Abstract: Rock avalanches is generally rapid downslope flowage of rock fragments composed of solid particles and some pore fluid. During rock avalanche slide, particle grading occurs, and certain sedimentation characteristics are exhibited in the deposit. For the study of kinematic sieving process in particle mass movement, the chute experiments have been conducted, and the sequence of particles with different size in vertical section and slide direction section are mainly studied. Then, based on the description of the vertical sorting and horizontal sorting, the grain-size distribution of the deposit zones is analyzed with sieve analysis, which presents larger grains prevail in the upper part of the deposit. The content of large particle exhibits double peak morphology of distribution in the slide direction section. The two distribution characteristics are also founded in Xinmocun rockavalanche and Pusacun rockavalanche, which are macroscopic reflection of the interaction of rock fragment during the particle flows and are important geological evidence for the study of rock avalanche kinematics. Finally, according to lots of chute experiments and case studies, the conclusion is proposed that:the dispersive pressure and kinematic sieving during the movement are main reasons for the formation of the vertical inverse grading and the longitudinal double peak morphology in the rock avalanche deposit. The kinematic sieving process energized by undulated sliding surface, and the momentum between particles.

       

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