恢复饱和系数的理论计算方法

Theoretical method for calculating the saturation recovery coefficient

恢复饱和系数是泥沙数学模型计算的重要参数，本文从理论上进一步研究了悬移质不平衡输沙的恢复饱和系数，提出了底部恢复饱和系数的概念，并推导了恢复饱和系数是底部恢复饱和系数和含沙量分布系数的乘积，从理论上合理解释了恢复饱和系数的取值问题。在既有研究成果的基础上，进一步推导了非均匀沙恢复饱和系数的计算式，计算结果表明不同粒径组的恢复饱和系数值是不同的，非均匀沙的平均恢复饱和系数应按沉速和级配的乘积加权平均计算，黄河下游通常水流条件（摩阻流速3～30cm／s）的平均恢复饱和系数约为0．1，平均底部恢复饱和系数为O．05—0．1，平均综合恢复饱和系数最小约为0．01，这和理论分析结果及黄河水沙数学模型的经验采用值基本相符。

The saturation recovery coefficient is an important coefficient in mathematic models for non-equilibrium transportation of suspended load. In this paper, the concept of bottom coefficient of saturation recovery is presented, and the saturation recovery coefficient is deduced to be the product of bottom coefficient of saturation recovery and distribution coefficient of suspended sediment concentration, which theoretically and reasonably explains the value selection of saturation recovery coefficient. Based on the previous study, the formulas to calculate the saturation recovery coefficient for non-uniform sediment are deduced. The results indicated that saturation recovery coefficient changes with grain size, and the average coefficient value of non-uniform sediment should be calculated in weighting average of the product of settling velocity and grain about 0.1 on normal flow condition （shear velocity gradation. The average coefficient value of saturation recovery is of 3 - 30cm/s） in the Lower Yellow River, the average bottom coefficient value of saturation recovery is about 0.05 - 0.1, and the minimum of average comprehensive coefficient of saturation recovery is about 0.01, which are accord with theoretical analysis and practical value of mathematic model in the Yellow River.