沉沙池超饱和输沙法恢复饱和系数研究

Study on the recovery saturation coefficient of over-saturation sediment transport in settling tanks

恢复饱和系数αi是一度流超饱和输沙法计算的重要参数之一,理论分析和实测资料表明,αi值与泥沙分组平均沉速ωi、摩阻流速U、池段平均水力坡度J等因素有关,是一个变幅较大的系数。用实测资料建立的αi值计算公式,其泥沙粒径范围为d=0.005～0.25mm,基本覆盖了黄河及长江中下游地区的泥沙粒径。在缺少相似已建沉沙池水流和泥沙特征实测资料条件下,且悬移质泥沙粒径d<0.25mm时,可用式(13)进行αi值计算。

The recovery saturation coefficient α_i is one of the important parameters in calculating the over_saturation sediment transport. The theoretical analysis and observed data show that α_i is related to the sediment mean fall velocity ω_i, frictional velocity U_*, and mean hydraulic slope J, and has a big value range. Based on the measured data,an expression is established to calculate sediment transport with size 0.005～0.25mm,which almost covers all sediment size in the Yellow River and the middle and lower Yangtze River. In the case of lacking measured data, the expression may also be used to settling tanks if the sediment size is less than 0.25mm.