钱塘江河口细颗粒泥沙起动流速研究

采用泥沙水槽试验研究了钱塘江河口不同粒径的泥沙起动流速。针对室内水槽试验水深条件的局限性,提出了以实测含沙量过程线拐点附近相应的垂线平均流速为泥沙起动流速的方法,得到了水深范围介于0.15～13.6m、中值粒径介于0.002~0.07mm的泥沙起动流速。张瑞瑾、窦国仁公式与沙玉清泥沙起动公式对比结果表明,各公式对于浅水深的水槽试验值均有较高的计算精度,而对于大水深起动流速均明显偏大。以张瑞瑾公式为基础,通过多元回归分析法修正有关系数,建立了适合于钱塘江河口细颗粒泥沙的起动流速拟合公式。

Study on incipient velocity of fine sediment in the Qiantang Estuary

A series experiments have been carried out in a sediment-flume to investigate the incipient velocity of fine sediment with different particle sizes.Aimed at the limitation of water depth condition in laboratory test,the incipient velocity of fine sediment was first defined as the vertically-averaged flow velocity at the inflection point of process curve about sediment concentration.The incipient velocity of fine sediment with median diameter between 0.002 and 0.07 mm in the water depth between 0.15 and 13.6 m was presented.With compare to the incipient formulas of sediment proposed by ZHANG Rui-jin,DOU Guo-ren and SHA Yu-qing,the conduction results demonstrate that all of the formulas have high computation precision in the shallow-water depth with the data from flume experiment,whereas a relatively large error of incipient velocity exists in the deep-water depth condition.Based on the correction coefficient of the formula proposed by ZHANG Rui-jin,a fitting formula of the incipient velocity for fine sediment in the Qiantang Estuary is developed by the multiple regression analysis.