Abstract Reduction of risks due to overtopping of coastal defences is an essential requirement for the design, management and adaptation of coastal structures. Extensive knowledge is available on the prediction of overtopping of smooth, sloping and vertical impermeable seawalls. The existing prediction methods provide less certain guidance for combined wind and swell conditions. This experimental study focuses on overtopping characteristics of coastal seawalls under random bimodal waves. Both unimodal and corresponding bimodal conditions were simulated under different slopes and crest freeboards. Proportions of swell in the bimodal sea were varied in each test. Mean wave overtopping discharges were calculated for non-breaking random waves over at least 1000 waves. EurOtop formulae agree closely with our measurements from the unimodal experiments whereas they underpredict the observed wave overtopping rates for bimodal conditions even when using the recommended Tm−1,0 period for such cases. A modification to the EurOtop formula is proposed on the basis of the experimental results, to better capture the overtopping discharge under bimodal conditions.

中文翻译：

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单向双峰海况下光滑不透水海堤的波浪漫顶

摘要 减少因海防越过造成的风险是沿海结构设计、管理和改造的基本要求。关于预测平滑、倾斜和垂直不渗透海堤的漫溢的广泛知识是可用的。现有的预测方法对组合风浪条件提供的指导不太确定。本实验研究侧重于随机双峰波作用下沿海海堤的漫顶特征。在不同的坡度和波峰干舷下模拟了单峰和相应的双峰条件。双峰海中的膨胀比例在每次测试中都不同。计算了至少 1000 个波浪中不间断的随机波浪的平均波浪越顶流量。EuroOtop 公式与我们在单峰实验中的测量结果非常一致，而即使在这种情况下使用推荐的 Tm-1,0 周期时，它们也低估了双峰条件下观察到的波浪越顶率。在实验结果的基础上，提出了对 EuroOtop 公式的修改，以更好地捕获双峰条件下的溢流。