Tsunami-like flow induced force on the structure: Prediction formulae for the horizontal force in quasi-steady flow phase
Tsunami-like flow induced force on the structure: Prediction formulae for the horizontal force in quasi-steady flow phase
复制标题
DOI：
10.1016/j.coastaleng.2021.103938
复制
发表时间：
2021-06
影响因子：
4.4
通讯作者：
S. Harish;V. Sriram;H. Schüttrumpf;S. Sannasiraj
中科院分区：
文献类型：
--
作者：
S. Harish;V. Sriram;H. Schüttrumpf;S. Sannasiraj
由于海啸等极端海岸事件，沿海地区结构的破坏需要更深入地了解流动行为，以改进设计准则。内陆传播海啸浪涌或海啸孔的特征是初始浪涌或海啸孔尖加气，然后逐渐增加水深（准稳流阶段）。在孔间相互作用过程中，结构首先经历脉冲压力，然后是孔内压力，这取决于结构障碍物宽度与流道宽度的比值（b/W）、来孔弗劳德数（Fr）、结构形状以及结构方向与流动方向的关系。通过2004年印度洋海啸和2011年东北海啸的现场调查和视频观测，发现海啸流准稳态时结构破坏占主导地位。此外，过去的大多数文献都集中在单一结构上的钻孔相互作用，而没有考虑流道效应（b/W）。因此，本实验研究对海啸类事件准稳定流过程中作用在矩形结构上的力的b/Wand - Fr效应提供了详细的见解。为了估计准定常流动阶段的水动力，我们采用了结合结构前部孔高（hf）和后部孔高（hr）的静水力方程。提出了一种基于质量和动量守恒的简化半解析方法来估计作用在矩形结构上的力。结果表明，这种力估计方法能合理地预测实验力-时程。由于设计指南使用流体动力阻力方程进行力估计，因此本研究还提供了阻力系数（Cd） forb/W> 0.2和Fr在0.6和2之间。在考虑Fr和b/W的同时，本研究试图提供一套封闭形式的准静力方程，为设计人员提供一种方便的力确定方法。
Destruction of the structures in coastal areas due to an extreme coastal event like a tsunami necessitates the deeper understanding of flow behaviour to improve the design guidelines. The characteristics of inland propagating tsunami surge or bore consist of an initial aerated surge or bore tip followed by the gradual increase in water depth (quasi-steady flow phase). During the bore interaction, the structure initially experiences an impulsive pressure, bore pressure followed by quasi-static pressure (quasi-steady flow phase) depending on the ratio of the structure obstruction width to flow channel width (b/W), incoming bore Froude number (Fr), the shape of the structure, and the orientation of structure to the direction of flow. From field surveys and video observations during the 2004 Indian Ocean Tsunami and the 2011 Tohoku tsunami, the structure failure during the quasi-steady state of tsunami flow is found to be predominant. Also, most of the literature in the past focused on the interaction of bore on a single structure in which the flow channelling effect (b/W) is not considered. Thus, the present experimental study gives a detailed insight into theb/Wand Fr effect in the force acting on the rectangular structure during the quasi-steady flow of tsunami-like events. To estimate the hydrodynamic force in the quasi-steady flow phase, we have adopted the hydrostatic force equation by incorporating bore height at the structure front (hf) and bore height at the structure back (hr). A simplified semi-analytical method is proposed based on conservation of mass and momentum to estimate the force on the rectangular structures. This approach of force estimation is showed to reasonably predict experimental force-time history. Since design guidelines use the hydrodynamic drag force equation for force estimation, the present study also provides the drag force coefficient (Cd) forb/W> 0.2 and Fr between 0.6 and 2. Along with the consideration of Fr andb/W, the study attempted to provide a closed-form set of equations to the quasi-static force, which helps designers with a convenient force determination method.