基于Rouse公式的紊流区悬沙粒径级配垂线分布规律

基于Rouse公式及紊流泥沙沉速公式,分别推导得到了紊流时的悬沙粒径及级配垂线分布公式,前者直接量化了泥沙“上细下粗”的垂线分布规律,后者则可用于计算不同水层及垂线上总的悬沙粒径级配。通过实例,应用粒径级配计算公式得到了不同水层的悬沙粒径级配。结果表明:泥沙粒径“上细下粗”的分布规律明显;在越远离床面的水层,细颗粒所占的比重越大,粒径分布越均匀。当考虑悬浮高度影响时,以最大粒径悬沙的最大悬浮高度为界,该高度之下级配“等宽”,该高度之上级配“上窄下宽”。

Vertical Distribution Law of Gradation of Suspended SedimentParticles in Turbulent Region Based on Rouse Formula

The vertical distribution formulas of suspended sediments’ particle size and gradation in turbulent flow region are derived respectively based on the Rouse formula and the formula of sediment particle settling velocities in turbulent flow. The former directly quantifies the vertical distribution law of sediment particles being “fine in the upper and coarse in the lower”, while the latter can be used to calculate the suspended sediment’s gradation in different water layers and the total gradation in vertical direction. The formula of particle size distribution is applied to a practical example to calculate the suspended sediment’s gradation in different water layers. Results suggest that the gradation is obviously in the law of “fine in the upper and coarse in the lower”. The farther away from the bed the water layer, the larger the proportion of fine particles, the more uniform the particle size distribution. In consideration of the influence of suspension height, the maximum suspension height of suspended sediments with the largest particle size is taken as the demarcation below which the gradation is in equal width, and above which the gradation distributes narrowly in the lower whereas widely in the upper.