二维条件下颗粒柱体崩塌入水堆积过程

在我国西南地区，以塔柱状危岩体崩塌为扰动源的涌浪次生灾害时有发生。涌浪特征与其扰动源的初始形状和破坏模式关系密切，塔柱状危岩体由下至上、空中崩解的破坏模式与颗粒柱体崩塌相似。区别于以往多试验采用的刚体材料和利用运动距离获得初始动力状态的涌浪试验，本研究设计并进行了不同高度和宽度的颗粒柱体在不同水深下自然崩塌的物理模型试验。运用PIV技术分析了颗粒体及水体的运动特征，按颗粒体与水体的相互作用关系将整个过程大致分为了3个阶段，并研究了颗粒柱体初始形态对试验结果的影响。结果表明，颗粒柱体崩塌后的残余体积受颗粒体初始形态影响较大，水深对其影响较小。涌浪产生早期，首浪位置与颗粒运动位置有着良好的对应关系；而后，两者的位置逐渐拉开。颗粒柱体高度越高，首浪最大波高出现时的位置与崩塌颗粒群前端位置的差值越大。这可能与流固相互作用后期水体流速大于颗粒流动速度有关。试验产生的涌浪大多具有完整波形，这与柱状颗粒体的散体性及其覆盖堆积特征对水体的作用呈不均匀性有关。涌浪传播过程中，水体在z方向上抬升幅度具有一定的渐变性。试验分析结果揭示了柱状危岩体引发涌浪的机制特点，为涌浪灾害防治提供了基础资料。

A study of the process of particle column collapsing into water under 2D condition

Impulsive wave and its secondary disasters, which are caused by the collapse of risky tower rocks, occur frequently in southwest China. Characteristics of the impulsive wave are closely related to the initial shape and failure mode of the disturbance source, the failure mode of collapse of risky tower rock mass from bottom to top and disintegrate in the air is similar to that of the collapse of granular column. Different from the rigid body materials and the motion distance to obtain the initial dynamic state used in the past wave test, this paper designs and carries out the physical model experiments of different heights and widths of particle column collapse at different water depths by using the PIV technology to analyze the movement characteristics of particle and water body.According to the interaction between particles and water, the whole process is roughly divided into three stages, and the influence of initial shape of particles on the test results is examined. The results show that the residual volume after the collapse of the granular column is greatly influenced by the initial shape of the granular body, while the water depth has little influence on it. There is a good corresponding relationship between the position of the first wave and the position of particle movement in the early stage of impulsive wave, and the distance between them began to increase. The higher the particle column is, the greater the difference between the position of the maximum wave height of the first wave and the position of the front end of the collapse particle group is, which may be caused by the fact that the velocity of the water body in the later stage of the fluid solid interaction is greater than that of the particle flow. Most of the generated waves have complete waveforms, which is related to the inhomogeneity of the effect on the water body caused by the covering accumulation characteristics of the columnar particle collapse and the dispersibility of columnar particles. The experimental results reveal the characteristics of the mechanism of the impulsive wave caused by the risky columnar rocks and may provide the basic data for the prevention and control of the surge disasters.