破碎波作用下淤泥含沙量分布试验研究

Experimental studies on sediment concentration distribution under breaking waves action along muddy coast

淤泥质海岸是我国海岸重要组成部分,其泥沙运动主要是"波浪掀沙,潮流输沙",在大风天破碎波作用下,水体含沙量剧增,对港口航道泥沙回淤会产生严重影响。以往研究沙和粉砂在破碎波作用下含沙量分布特征的较多。本次试验采用自来水和徐圩航道试挖槽内原状泥调配得到的试验淤泥,通过室内1∶200缓坡长水槽试验,分析研究崩破波作用下淤泥密度分别为1.35,1.40和1.45 kg/L的水体含沙量分布特征及掀沙机理。分析研究结果表明:破碎波掀沙能力与床面淤泥密度有较强的非线性关系。淤泥密度小于1.45 kg/L时,在破波点之前,底部就开始形成高含沙区,在破波点附近达到最大,在破波点后一定距离,水体明显出现泥沙分层现象。底部含沙量较大时,破碎波作用下淤泥与粉砂含沙量垂线分布特征相似都不均匀。

The muddy coast is an important part of China＇s coast, and the wave-lifted sand and tide-transported sand are the main forms of sediment movement along the muddy coast. The sediment concentration is rapidly going up during heavy storm waves. The high sediment concentration can cause terrible sediment back-silting within the ports and waterways. In the past, the experimental studies mainly focused on sand and silt concentration under breaking waves. In this study, wave-current flume test studies are carried out for the distribution characteristics of the sediment concentration and mechanism of lifted sand under spilling waves action, in which the gentle slope （ 1 ： 200） is set up for testing wave movement. The distribution characteristics of the mud concentration having mud density of 1.35,1.40,1.45 kg/L and mechanism of the wave-lifted sand by the action of the spilling waves have been analyzed respectively through the flume tests. The mud for model tests is taken from the trial excavating channel for the Xuwei waterway. Research results show that the capacity of the breaking wave-lifted sand and the mud density have the strong nonlinear relationships. And the bottom becomes a high sediment concentration area beyond the wave breaking point, the sediment concentration is up to the maximum around the wave breaking point, and there is water stratification behind a certain distance when mud density is less than 1.45 kg/L. When there is a greater sediment concentration in the bottom, the vertical distribution characteristics of both mud and silt concentration are nonuniform under the breaking waves action.