山区卵砾石河道水流阻力计算  

Flow resistance evaluation in gravel-and boulder-bed

作　　者：罗铭[1] 黄尔[1] 王协康[1] 杨奉广[1] LUO Ming;HUANG Er;WANG Xiekang;YANG Fengguang(State Key laboratory of Hydraulics and Mountain River Engineering,Sichuan University,Chengdu 610065,China)

机构地区：[1]四川大学水力学与山区河流开发保护国家重点实验室,四川成都610065

出　　处：《水科学进展》2020年第3期404-412,共9页Advances in Water Science

基　　金：国家重点研发计划资助项目(2017YFC1502503);国家自然科学基金资助项目(41771543)。

摘　　要：卵砾石河道广泛存在于山区河流中,在卵砾石河床近底层的水流流速低于上方流速,速度剖面出现拐点,类似于自由剪切流动,传统的指数型和对数型水流阻力公式计算误差偏大。将自由剪切流理论类比到山区卵砾石河道,并考虑山区河流特殊流态、流场和剪切力的影响,引入雷诺数(Re)、弗劳德数(Fr)和摩阻流速利用水槽数据进一步修正了该类水流阻力公式。筛选位于意大利南部的亚平宁山脉140条山区河流野外数据对新公式进行验证,并检验对比了已发表的多个山区河流阻力公式。结果表明:修正后的水流阻力公式Nash-Sutcliffe效率指数最接近1、均方根误差最小、相对误差最小。自由剪切流动的类比是从湍流结构角度推导河道水流阻力,能更好地阐释特殊水流结构,进而提高计算精度。The standard exponential and logarithmic flow resistance laws in shallow streams with gravel-and boulder-bed cannot be adapted. Field investigations suggest that the flow velocity near gravel bed is lower than that of the upper flow,similarly to the mixing layer flow. In this study,the newly mixing layer analogy is applied theoretically for deducing the flow resistance law by introducing the Reynolds number,Froude number,and shear velocity,which is respectively affected by flow regime,flow condition,and shear stress. Most field data located in 140 mountainous streams located at the Apennines in Italy are selected to calibrate and compared with other resistance laws of mountainous streams. The results show that the novel multivariable mixing layer law is characterized by the most closed-1 Nash-Sutcliffe efficiency index,lowest root mean square error and relative error. This mixing layer approach is based on an entirely different view of shallow gravel stream turbulence,which interprets the flow structure and improves the calculation accuracy.

关 键 词：山区河流 卵砾石河道 阻力系数 自由剪切流 亚平宁山脉 

分 类 号：TV133[水利工程—水力学及河流动力学]