采用水槽物理模型试验,观察泥沙在不同工况下的起动情况.通过测量相应断面的波高和近底流速,计算泥沙起动临界波高和最大床面剪切力.将计算结果与观测的泥沙起动情况相结合,分析波浪作用下植物对泥沙起动的影响.试验结果表明:随着植物密度的增加,波高有所减小.当波高小于泥沙临界起动波高时,泥沙将不会起动.通过计算近底最大流速,得到最大床面剪切力,发现:最大床面剪切力在同一植物密度下沿波浪传播方向逐渐减小,而同一断面最大床面剪切力随着植物密度的减小而增加.根据试验观测泥沙起动现象可知,植物密度的增加能有效地减少泥沙起动,更好地保护床面.%Based on the flume model experiment,the incipient motion of sediment under different working conditions is observed.By measuring the wave height and the near-bed velocity of the corresponding section,the critical wave height and the maximum bed shear force of sediment initiation are calculated,and the calculated results are combined with the observed initial sediment movement to analyze the effect of plants on the sedi-ment start-up under wave action.The results show that the sediment will not start up when the wave height is smaller than the critical sediment onset wave height as plant density increases.The maximum bed shear force was calculated by using the maximum near-bed velocity.It was found that the maximum bed shear force decreased along the wave propagation direction at the same plant density,while the maximum bed shear force of the same section increases with the decrease of plant density.According to the experimental observation of sediment start-up phenomenon,the increase of plant density can effectively reduce the sediment start-up and better protect the bed surface.
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