Study on a mechanism of sheet-flow sediment transport

面流输沙机理研究

• 批准号: 03650429
• 负责人: ASANO Toshiyuki
• 金额: $ 1.02万
• 依托单位: Kagoshima University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03650429/
• 关键词: Sheet-flow; Beach change; Sediment transport; Stormy wave; boundary layer Oscillatory; mixture Sediment-fluid; Saltation; Particle dynamics; シ-トフロ-漂砂

Study on sheet-flow sediment transport has recently attracted much interest because severe beach erosions and shoalings of fairway occur under this mode. There have been many studies on sediment transport under low fluid tractive force. In comparison, the behavior of fluid/sediment mixture under high fluid tractive force is poorly understood. In this study, motions of sediment particles under oscillatory flows were measured with a high speed video camera, and the properties were carefully analyzed. The main results are as follows.(1) The thickness of the sheet flow layer increases almost linearly with the Shields parameter. Meanwhile the thickness of the saltation layer does not increase with it noticeably.(2) The profile of sediment concentration can be represented by an exponentially decay curve in the saltation layer, and an upward convex curve in the sheet-flow layer.(3) The sediment transport rate was measured by the following two ways. One is estimated by the product of sediment concentration and sediment transport velocity, the other is to direct-trace a group of painted particles in the video frame. As a result, the two methods yield little difference in the obtained sediment transport rate. Little difference is also found between particle materials used as the sediment.(4) The obtained sediment transport rates are plotted in the center of scatters reported by other researchers previously. The results also agree well with those predicted by Madsen-Grant formula.(5) Although this investigation does not cover a very wide experimental range, the above obtained results yield useful information on the mechanics of the sheet-flow and quantitative description of the sediment transport.

片流输沙模式下的海滩冲刷和航道变浅等问题日益引起人们的关注。关于低水动力条件下的泥沙输移问题，已有许多研究。相比之下，流体/沉积物混合物在高流体牵引力下的行为知之甚少。本研究利用高速摄影机量测泥沙颗粒在振荡水流下的运动，并分析其特性。主要结果如下。(1)薄层流动层的厚度几乎随Shields参数线性增加。同时跃变层的厚度并不随其显著增加。(2)在跃移层中，含沙量的分布曲线为指数衰减曲线，而在片流层中，含沙量的分布曲线为上凸曲线。(3)输沙率的测定采用以下两种方法。一种是通过泥沙浓度和输沙速度的乘积来估计，另一种是直接跟踪视频帧中的一组着色颗粒。结果表明，两种方法得到的输沙率相差不大。在用作沉积物的颗粒材料之间也发现几乎没有差异。(4)所得到的输沙率分布在其他研究者所报道的散射中心。计算结果与Madsen-Grant公式预测的结果吻合较好。(5)虽然这项调查并没有涵盖很宽的实验范围，上述获得的结果产生有用的信息的机制，片流和泥沙输运的定量描述。

项目成果

Toshiyuki Asano: "Observations of granular-fluid wixture under an oscillatory sheet flow" Proceedings of 23rd International Confer-ence on Coastal Eugineering. (1992)

Toshiyuki Asano：“振荡片流下颗粒流体混合物的观察”第 23 届国际沿海工程会议论文集。

浅野 敏之・中野 康弘,玉井 賢治: "振動流作用下におけるシートフロー状態の漂砂量の測定" 海岸工学論文集. 40. (1993)

Toshiyuki Asano、Yasuhiro Nakano、Kenji Tamai：“振荡流作用下片流状态下的沙漂量测量”，海岸工程学报 40。（1993）。

浅野 敏之・中野 康弘・玉井 賢治: "振動流作用下におけるシートフロー状態の漂砂量の測定" 海岸工学論文集. 40. (1993)

Toshiyuki Asano、Yasuhiro Nakano、Kenji Tamai：“振荡流作用下片流状态下的沙漂量测量”，海岸工程学报 40。（1993）。

Toshiyuki Asano, Yasuhiro Nakano and kenji Tamai: "Measurements on sheet flow sediment transport under oscillatory flows" Proc. of Coastal Engineering. Vol. 40. (1993)

Toshiyuki Asano、Yasuhiro Nakano 和 kenji Tamai：“振荡流下片流沉积物输送的测量”Proc。

Toshiyuki Asano: "A model on oscillatory flows over plain movable bed" Proc. of Inter. Conf. on Multiphase Flows. Vol. 1. 109-112 (1991)

Toshiyuki Asano：“普通可移动床上的振荡流模型”Proc。