Study on Unequilibrium Sediment Transport Rate and Local Scour around Structures

建筑物周围不平衡输沙率与局部冲刷研究

• 批准号: 61550365
• 负责人: SAWAMOTO Masaki
• 金额: $ 1.09万
• 依托单位: TOHOKU 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: 1986
• 资助国家: 日本
• 起止时间: 1986 至 1987
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-61550365/
• 关键词: Local scour; Cylinder; Wave; Sand Drift; 非平衡性漂砂量

Following three items were studied.1) Dynamic roll of nonequilibrium of sediment transport on bottom topography change under the wave action: The stability of sand bed was analysed theoretically. It was confirmed that the nonequilibrium of sand transport and scattering of step length are necessary for existance of single dominant length of bottom topograpy although asymmetry of sand transport rate make the bed unstable. The results were reported in the first reference.2) Sediment transport rate in sheet flow regime: A series of experiment on sediment transport phenomena were carried out in sheet flow regime using an U-shape tube. Sediment transport rate, sediment motion and velocity distributions were measured. The 1.5 power relationship between transport rate and the bed shear stress was concluded. The limit of sheet flow regim was also discussed. The results were reported in the second reference.3) Local scour around a cylinder under the wave action: A series of experiments were performed in a wave tank. The observed shapes of scour were classified into two category. The mechanism of scour was discussed considering the interaction of the flow and the bed. The roll of shedded vortices was confirmed through the flow visualization technique.

1)波浪作用下输沙不平衡对底面地形变化的动力滚动：对沙床稳定性进行了理论分析。虽然输沙率的不对称性使河床不稳定，但输沙量的不平衡和步长的散布是底面地形单一优势长度存在的必要条件。2)片流输沙速率：利用U型管对片流输沙现象进行了一系列实验研究。测量了泥沙输移速率、泥沙运动和流速分布。得出了输沙率与床面剪切力之间的1.5次幂关系。文中还讨论了薄层流区的极限。3)波浪作用下圆柱体周围的局部冲刷：在波浪水池中进行了一系列试验。观测到的冲刷形态可分为两类。考虑水流与河床的相互作用，对冲刷机理进行了探讨。通过流动显示技术确定了脱落涡的卷曲。

项目成果

Sawamoto,M.: "Sediment Transport in Sheet Floe Ragime" "Coastal Sediment'87", WW Div./SCE. 415-423 (1987)

Sawamoto,M.：“片状浮冰 Ragime 中的沉积物输送”“沿海沉积物 87”，WW Div./SCE。

Nishizawa,M.: Proc.of 6th APD-IAHR Congress. (1988)

Nishizawa,M.：第六届 APD-IAHR 大会议程。

Sawamoto,M;Yamashita,Y: Coastal Sediment 87'. (1987)

泽本，M；山下，Y：沿海沉积物 87。