Research about the variability of sand size inside the hopper of a trailing suction dredger has yet to be done, despite its importance for beach nourishment projects. In this study, several samples were taken using different methodologies during dredging for a particular case of beach nourishment on board one dredger. Sampling was carried out with a tube core and a Van Veen grab at the surface when the hopper was full of sand. The results showed problems with the Van Veen grab, the standard methodology used for sampling aboard a dredger. This method should be reconsidered in the future because surface samples were not representative of the whole hopper due to the bias of higher percentage of shell pieces. According to the results, the core tubes introduced by percussion were the only useful method in determining average sand parameters closer to the values obtained for the borrow site. Moreover, cores also showed a linear correlation between sand size and depth: D50 increased 20% from the surface to 1 m depth; this is a sixth of the hopper depth of this study case. Regrettably, the manual percussion procedure could not reach depths greater than 1 m.

中文翻译：

---

用于海滩营养的拖吸式挖泥船料斗内的沙粒大小可变性

尽管拖吸式挖泥船料斗内沙子大小的变化对海滩营养项目很重要，但尚未进行研究。在这项研究中，在一艘挖泥船上的特定海滩营养案例中，在疏浚过程中使用不同的方法采集了几个样本。当料斗装满沙子时，使用管芯和表面的 Van Veen 抓斗进行采样。结果表明 Van Veen 抓斗存在问题，这是在挖泥船上取样的标准方法。这种方法应该在未来重新考虑，因为表面样品不能代表整个料斗，因为较高百分比的壳片存在偏差。根据结果​​，通过冲击引入的芯管是确定更接近取土场获得的值的平均砂参数的唯一有用方法。此外，岩心还表现出砂粒大小和深度之间的线性相关性：D50 从地表到 1 m 深度增加 20%；这是本研究案例料斗深度的六分之一。遗憾的是，手动敲击程序无法达到大于 1 m 的深度。