潜堤对海啸波作用下岸滩剖面变化影响试验

Experimental study on sandy beach profile changes by tsunami waves under effect of submerged breakwater

基于波浪水槽试验,对潜堤能否有效减少海啸岸滩冲刷问题开展研究。选取孤立波作为入射波,考虑不同潜堤位置和堤顶水深情况,同时选取没有修建潜堤时海啸岸滩变化试验结果进行对比分析。实验对波高、流速、地形变化以及孤立波的上爬、回落等全过程进行测量和记录。研究结果表明,潜堤的修建并不能有效减少海啸对岸滩的冲刷,仅能改变淤积沙坝的高度和位置,且会造成潜堤离岸侧局部略有淤积,向岸侧会出现明显的局部冲刷坑。潜堤位于水跃发生区域时,对减小岸滩淤积沙坝高度效果最为明显。保持堤顶水深不变,减小潜堤的离岸距离,对减少最大局部冲刷深度效果更为明显。

A series of two-dimensional experiments were performed to investigate whether or not submerged breakwater could effectively reduce the tsunami scouring on the sandy beach.The incident wave was solitary wave.The different location of submerged breakwater and depth of submergence were considered respectively in this study.The comparative study was also carried out to make a comparison with sandy beach profile changes by tsunami waves without submerged breakwater.The free surface elevations,flow velocity,processes of wave uprush and back wash,the change of cross-shore beach profile were measured and recorded.The experimental result showed that the submerged breakwater could not effectively reduce the tsunami scouring on the sandy beach and could influence the height and position of deposition sand bar.At same time,there was a deposition on the off-shore side of submerged breakwater and a scouring on the onshore side.The effect of reducing the deposition sand bar could be obvious when the submerged breakwater located in the hydraulic jump took place.The maximum local tsunami scour depth could decrease,as depth of submergence kept and offshore distance of submerged breakwater decreased.