【摘要】 通过对不同几何结构和护面材质的海堤开展大量组次物理模型试验,得出越浪水体强烈的剪切力导致的后坡侵蚀和护面块体滑动被证明是海堤失稳的主要触发因素。建议工程标准和规范中考虑越浪流速和剪切力,将有利于溃堤风险的评估和预判。然而实验数据显示,海堤在越浪强度递增过程中的受压达到峰值的先后顺序为堤顶-挡浪墙-后坡。因此,瞬时水动力冲击导致的疲劳性破坏可能是另一种溃堤机理,虽没有在试验中出现,但需要时刻警惕。不同于广泛使用的允许越浪量,本项工作提出了针对我国沿海典型海堤类型的溃堤越浪量阈值建议值。这使得通过经验公式计算和预测溃堤风险变成可能。溃堤越浪量很大程度上受护面材质、后坡坡度和挡浪墙高度影响,但在试验中没有体现对堤顶宽度的敏感性。试验结果表明,对于相同的海堤结构和堤顶高程,相对于没有挡浪墙的海堤增设挡浪墙有可能是对海堤稳定性的一种降低。但这还需要进一步被其他研究者和工程师讨论验证。更多还原

【Abstract】 This study as one of the keys in the marine hazard mitigation service system in China reveals explicitly the major mechanism of sea dike failure caused during wave overtopping.A large number of groups of wave flume experiments conducted for the sea dikes with different geometric structures and armor block materials indicate that the landward slope erosion and the armor block sliding of the dike caused by strong shearing force of the overtopping water body are proved to be the major trigger factors for the sea dike instability.It is,therefore,recommended that the competent velocity and shearing force of the overtopping process should be taken into account in the engineering standards and specifications,which would be helpful to the evaluation and anticipation of the dike failure risk.However,the experimental data indicate that the order of the peak pressures that the sea dike experienced in the overtopping process is dike top-wave wall-landward slope.Therefore,the fatigue failure caused by the instantaneous hydrodynamic impact might be probably another mechanism of the dike failure.Although this does not occur in the experiments,it should be kept in mind always.Instead of the tolerable overtopping rates that have been adopted widely,the recommended values of the wave overtopping threshold causing the sea dike failure are proposed for the typical types of sea dikes present along the coast of China.This makes the empirical formula calculation and prediction of the dike failure risk becomes possible.The overtopping rate for the dike failure is to a large extent influenced by the armor block material,the falling gradient of the landward slope and the height of the wave wall,but shows little sensibility to the width of the dike top in the experiments.The experimental results show that under the case that the sea dike has the same structure and dike-top elevation,the adding of wave wall may reduce the stability of the sea dike,relatively to the dike without wave wall.But,this will need to be tested and verified further by other researchers and engineers in the future.更多还原