Study on sediment transport mechanism in swash zone considering in- and ex-filtration effects of a foreshore sandy beach

考虑前滨沙滩入渗和排渗效应的冲沙带输沙机制研究

• 批准号: 11650533
• 负责人: ASANO Toshiyuki
• 金额: $ 1.86万
• 依托单位: Kagoshima University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650533/
• 关键词: swash zone; porous sand layer; sediment transport; run-up waves; percolation; ground water table; beach deformation

Several workers have pointed out the importance of the groundwater flow in a sandy tidal beach on stability and deformation processes of the foreshore slope. The quantitative descriptions of the effects on sediment transport rates in swash zone, however, have not been sufficiently studied. The present study has evaluated the in- and ex-filtration effects on the sediment transport by analyzing the flow fields both for on a slope and inside the porous medium.In the first year, a transient infiltration flow into a sand basement, which simulates percolation process of run-up waves, has been analyzed by expanding Dicker's unsteady seepage flow theory. For a description on the run-up wave motion, a numerical model with moving boundary treatment has been used. As a result, the wave velocities on a sandy slope are little affected by the seepage flow, and the infiltration velocities do not show unsteady properties even though the imposed pressure variations are highly unsteady. Next, motions of a sediment particle under both flow motions by run-up waves and by seepage flows are discussed. Analytical expressions on the critical tractive force and sediment transport rate including in- and ex-filtration effects have been derived.In the second year, an analytical non-linear wave theory has been adopted in order to improve accuracy on the velocity field compared to the first year. Using obtained wave motions, a spherical particle motion placed on a slope is traced based on the equation of motion. The characteristics of the sediment motions and resultant sediment transport rate have been discussed.

一些学者指出了砂质潮滩地下水流动对前滩边坡稳定性和变形过程的重要性。然而，对冲积带输沙速率影响的定量描述还没有得到充分的研究。本研究通过分析坡面和多孔介质内部的流场，评价了入滤和出滤对泥沙输运的影响。本文首先通过对Dicker非定常渗流理论的扩展，分析了模拟升压波渗流过程的砂基瞬态入渗流。采用了移动边界处理的数值模型来描述助跑波的运动。结果表明，沙质边坡上的波速受渗流的影响较小，入渗速度不表现出非定常特性，尽管施加的压力变化是非定常的。其次，讨论了泥沙颗粒在上升波和渗流作用下的运动。导出了临界牵引力和输沙速率的解析表达式，包括滤入和滤出效应。在第二年，为了提高速度场的精度，采用了解析型非线性波动理论。利用获得的波动，根据运动方程跟踪放置在斜坡上的球形粒子的运动。讨论了泥沙运动的特征和由此产生的输沙率。

项目成果

浅野敏之: "前浜砂層内の浸透流を考慮した波打ち帯の漂砂の解析"海岸工学論文集. 第47巻. 511-515 (2000)

Toshiyuki Asano：“考虑前滩沙层内渗流的起伏带沙流分析”海岸工程杂志第 47 卷 511-515（2000 年）。

Hoque Azharul: "Calculation on sediment particle trajectory placed in swash zone"平成12年度土木学会西部支部研究発表会講演概要集. 第2巻(印刷中). (2001)

Hoque Azharul：“斜流带沉积物颗粒轨迹的计算”2000 年日本土木工程师学会西部分会研究报告摘要第 2 卷（2001 年出版）。

Toshiyuki Asano: "Analyses on sediment transport in a swash zone considering infiltration flows into a sandy foreshore slope."Proc.of Coastal Engrg., JSCE. Vol.47. 511-515 (2000)

Toshiyuki Asano：“考虑渗透流进入沙质前滨斜坡，分析冲刷带中的沉积物迁移。”Proc.of Coastal Engrg.，JSCE。

米永敏之: "浸透性斜面上の遡上波の運動と岸沖漂砂の数値解析"平成11年度土木学会西部支部研究発表会講演概要集. 第2巻. 316-317 (2000)

Toshiyuki Yonega：“透水斜坡上的上升波浪运动和海上沙流的数值分析”1999 年日本土木工程师学会西部分会研究报告摘要第 2 卷。316-317（2000）。

Toshiyuki Yonenaga: "Numerical Simulations on run-up waves and on-offshore sediment transport on a porous sloping sand bed."Proc.of Western Branch of Civil Engineers. Vol.2. 316-317 (1999)

Toshiyuki Yonenaga：“多孔倾斜沙床上的助跑波和近海沉积物输送的数值模拟”，土木工程师西部分会的论文。