ISSN 1000-3665 CN 11-2202/P
    刘世涛, 程谦恭, 林棋文, 姚志勇, 孙先锋, 邓凯丰, 刘道胜, 王进华. 碎屑集合体撞击与停积过程的运动学特征研究[J]. 水文地质工程地质, 2021, 48(6): 140-150. DOI: 10.16030/j.cnki.issn.1000-3665.202009025
    引用本文: 刘世涛, 程谦恭, 林棋文, 姚志勇, 孙先锋, 邓凯丰, 刘道胜, 王进华. 碎屑集合体撞击与停积过程的运动学特征研究[J]. 水文地质工程地质, 2021, 48(6): 140-150. DOI: 10.16030/j.cnki.issn.1000-3665.202009025
    LIU Shitao, CHENG Qiangong, LIN Qiwen, YAO Zhiyong, SUN Xianfeng, DENG Kaifeng, LIU Daosheng, WANG Jinhua. Study on kinetic characteristics of the collision and emplacement of grains aggregation[J]. Hydrogeology & Engineering Geology, 2021, 48(6): 140-150. DOI: 10.16030/j.cnki.issn.1000-3665.202009025
    Citation: LIU Shitao, CHENG Qiangong, LIN Qiwen, YAO Zhiyong, SUN Xianfeng, DENG Kaifeng, LIU Daosheng, WANG Jinhua. Study on kinetic characteristics of the collision and emplacement of grains aggregation[J]. Hydrogeology & Engineering Geology, 2021, 48(6): 140-150. DOI: 10.16030/j.cnki.issn.1000-3665.202009025

    碎屑集合体撞击与停积过程的运动学特征研究

    Study on kinetic characteristics of the collision and emplacement of grains aggregation

    • 摘要: 青藏高原高山峡谷区常发育崩滑碎屑流,这种灾害具有发育边坡高陡、碎屑流高能且坡脚撞击剧烈等特点。为了解这种碎屑流的运动规律及其堆积特征,设计并建立了自由下落的碎屑集合体撞击与停积过程的模型实验装置。考虑撞击过程对碎屑流运动和堆积的影响,获取不同粒径大小、体积、下落高度条件下,碎屑集合体的运动与堆积图像和定量化数据,并据此观察分析碎屑流的运动规律和堆积特征。主要结论如下:(1)碎屑集合体底部首先撞击地面,随后颗粒挤压形成剪切面,颗粒在剪切面上进行扩散运动并最终堆积。(2)撞击阶段,颗粒之间显著的动量传递作用致使碎屑集合体前缘颗粒运动速度较快、距离更远,并产生离散堆积现象。(3)自堆积重心至边缘,碎屑集合体的堆积厚度逐渐减小;堆积形态在运动初期呈近圆形,最终形态呈近菱形;运动中的力学过程导致出现横向脊和X型共轭脊现象。(4)碎屑集合体的粒径越小,体积越大,其主体运动距离、主体覆盖面积越大以及运动速度越快;体积与最大堆积厚度呈正相关关系;下落高度越小,其最大堆积厚度越大,运动速度越慢,与主体覆盖面积大体上呈负相关关系。(5)体积条件对碎屑集合体的堆积特征影响最大,粒径大小其次,下落高度影响最小。该研究可为川藏铁路沿线的工程结构设计及碎屑流的防治工作提供理论基础。

       

      Abstract: Debris avalanches are frequently occurred in the mountainous region along the Sichuan-Tibet Railway in the Tibetan Plateau. These disasters are characterized by high and steep slope, huge energy and intense impact at the slope toe. In order to study the propagation behaviours and dynamic mechanisms of the debris avalanche, a series of laboratory experiments that grains aggregation freefall and impact on the horizontal plane then settle on it was conducted. In laboratory experiments, we consider the influences of the collision on the propagation and deposition features of debris avalanches. Images and quantitative data of the propagation and deposit features of the grains aggregation under the conditions of different particle sizes, volumes and falling height are obtained. The results show that (1) the bottom of the grains aggregation first hits the ground, then the particles are squeezed to form a shear surface. The particles move along the shear surface, spread and eventually deposit; (2) During the collision phase, the significant momentum transfer between the particles cause the particles at the front edge of the grains mass to move faster and farther, resulting in dispersive deposit; (3) From the center of the mass to the frontal edge of the deposit, the thickness gradually decreases; the shape is nearly circular at the beginning of the movement, and the final form is nearly diamond. The mechanical process leads to the occurrence of stress ridges; (4) The smaller the particle size of the grains aggregation is and the larger the volume is, the larger the maximum deposit thickness, the farther the travel distance of the main body, and the larger the main body cover area, the faster the spreading speed; the smaller the falling height is, the larger the maximum deposit thickness, the slower the spreading speed, which leading to a decreasing trend of the main body cover area; (5) Volume have the greatest influences on the deposit features of debris avalanches, followed by particle size, and the falling height has the least influence.

       

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