A Study on the Origin of Step-Pool Formation in A Mountain Stream Considering the Water Surface Waves.

考虑水面波浪的山涧阶梯池形成成因研究。

• 批准号: 07650585
• 负责人: HASEGAWA Kazuyoshi
• 金额: $ 1.28万
• 依托单位: HOKKAIDO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650585/
• 关键词: mountain streams; step and pools; rib bed; supercritical flow; water surface waves; anti-dunes; linear stability analysis; formation condition of bed waves; 渓流; 山地河川; ステップ・プール; 河床波; 発生条件; 水面・河床相互干渉

Experiments of ribs and step & pools formation using a laboratory flume with sand-gravel bed, and theoretical analysis for the origins were conducted. They resulted in the followings :(1) In the supercritical flow condition, ribs were formed on the bed, which had a 2-dimensional transversal shape, with active sediment transport and with stagnation of the maximum size stones on the crests.(2) With the trigger of rib formation, 3-dimensional diagonal waves were generated on the water surface.(3) When the resonant condition between water surface wave and rib arose, the water surface waves stood with large amplitudes and deformed the bed waves into 3-dimensional undulations very rapidly.(4) However, the resonant state was not continued so long time ; both the water waves and bed waves ceased to exist with short duration. Only when the water supply was stopped during the occurrence of resonant state, step & pools were found on the bed.(5) Partial occurrence of step & pool system were caused … More by the beat phenomenon between water surface waves and bed waves, which was yielded with different but close wave lengths of them.(6) Multi modal step & pool systems could be found in the channel ; they arose with corresponding to the transverse mode of diagonal water surface waves.Linear stability analysis for the movable boundary, using the plane 2-dimensional momentum equations with non-hydrostatic pressure distribution, revealed the followings :(1) The theoretical step & pool wave length to give the maximum growth rate agrees with the experimental step & pool wave lengths well.(2) Extent of unstable wave number with which step & pools grow up is very narrow, and hence it causes the rapid failure of the step & pools.(3) It can be understood from the analysis that step & pools are 3-dimensional anti-dunes which are formed by the resonant effect of diagonal water surface waves.(4) Concerning with ribs, the unstable wave number domain corresponding to the experimental one is rather difficult to be derived theoretically. Improvement of the theory is needed to apply it to the design of artificial ribs and step & pools. Less

利用室内砂卵石床水槽进行了滩肋和阶跃池形成的实验研究，并对滩肋和阶跃池的成因进行了理论分析。结果表明：（1）在超临界水流条件下，床面上形成肋状结构，呈二维横向，输沙活跃，最大粒径的卵石在顶部停滞。(2)在肋的触发下，在水面上产生三维斜向波。(3)当水面波与肋板发生共振时，水面波具有较大的振幅，并迅速地将底波变形为三维波浪。(4)然而，共振状态并没有持续这么长的时间，水波和床波都消失了，持续时间很短。只有在发生共振状态时停止供水，才能在床面上发现台阶和水池。(5)造成部分梯级&水池系统的出现 ...更多信息 由于水面波和底波的波长不同而又相近，产生了拍频现象。(6)采用二维非静水压力分布的动量方程，对可动边界进行线性稳定性分析，结果表明：（1）计算最大增长率的理论步长和池波长与实验步长和池波长吻合较好; (2)台阶池发育的不稳定波数范围很窄，导致台阶池的快速破坏。(3)通过分析可知，阶池是斜向水面波共振作用形成的三维反沙丘。(4)对于肋，理论上很难导出与实验结果相对应的不稳定波数域。这一理论尚需进一步完善，才能应用于人工肋和阶梯水池的设计。少

项目成果

Kanbayashi, S.and K.Hasegawa: "Linear analysis of the origin of step-pool systems, Proc.of Hokkaido Branch of JSCE" No.53 (B) (in Japanese). 32-37 (1997)

Kanbayashi, S. 和 K.Hasekawa：“阶梯池系统起源的线性分析，JSCE 北海道分会论文集”No.53 (B)（日语）。

Hasegawa, K.: "Hydraulic characteristics of mountain streams and their practical applications" Text of the Summer School for Hydraulic Engineering, Committee of the Hydraulics of JSCE. (in Japanese). A-9-1-A-9-20 (1997)

Hasekawa, K.：“山间溪流的水力特性及其实际应用”，JSCE 水力学委员会水利工程暑期学校文本。

長谷川 和義: "渓流における淵・瀬(ステップ・プール)の形成機構とその設計指針" 水工学論文集. 40. 893-900 (1996)

长谷川一义：“山间溪流中深水（台阶和水池）的形成机制及其设计指南”《水利工程学报》40. 893-900（1996）。