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分段式潜堤对岛礁上孤立波水动力特性的影响

Effects of segmented submerged breakwater on hydrodynamic characteristics of solitary waves over coral reefs

  • 摘要: 近年来,热带及亚热带岛屿因珊瑚礁退化导致天然消波能力下降,面临日益严峻的海啸灾害风险。传统连续式潜堤虽能有效衰减波浪能量,但其封闭结构易阻碍礁坪水体交换,引发水位壅高及底部侵蚀等问题。为此,本研究提出一种适用于珊瑚礁地形的分段式潜堤布置方式,通过非连续实体单元与间隙区域的组合设计,在保障消波效能的同时优化水体交换能力。基于波浪水槽物理模型试验,系统探究了分段式潜堤对孤立波传播过程中无量纲最大波高、反射系数、透射系数及波浪最大爬高的影响机制。结果表明:分段式潜堤的存在会对孤立波在岛礁上传播演变特性产生显著影响。分段式潜堤可通过增强波浪反射与潜堤中部绕射协同作用,降低传播至礁坪上的最大波高;在入射波高较大时(H≥0.08 m),分段式潜堤中部区域的湍流耗散效应可以显著降低透射波高,且波浪最大爬高随礁坪水深与入射波高的增加单调递增;分段式潜堤附近的复杂流场会耗散大量的波浪能量,导致礁后斜坡上的波浪最大爬高降低,实现防浪护岸的作用。

     

    Abstract: In recent years, tropical and subtropical islands have faced increasing risks of tsunami due to the degradation of coral reefs and consequent decline in natural wave-dissipation capacity. Although traditional continuous submerged breakwaters can effectively attenuate wave energy, their enclosed structures tend to impede water exchange on reef flats, leading to water level elevation and seabed erosion. To address these issues, this study proposes a segmented submerged breakwater configuration adapted to coral reef topography, which is composed of discontinuous solid units and gap areas to maintain wave attenuation performance while optimizing water exchange. Through physical model experiments in a wave flume, we systematically investigated the mechanisms by which segmented submerged breakwaters influence the dimensionless maximum wave height, reflection coefficients, transmission coefficients, and maximum wave run-up height during solitary wave propagation. The results show that the presence of the segmented submerged breakwater significantly affects the propagation and evolution of solitary waves on the reef. The segmented submerged breakwater can enhance the synergistic effect of wave reflection and gap diffraction, thereby reducing the maximum wave height transmitted to the reef flat. When the incident wave height is large, the turbulent dissipation effect in the middle area of the segmented submerged breakwater can significantly reduce the transmission wave height, and the maximum wave height increases monotonically with the increase of submergence water depth and incident wave height. The complex flow field near the breakwater dissipates a large amount of wave energy, thereby reducing in the maximum wave height on the backreef slope and achieving the purpose of wave prevention and embankment protection.

     

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