沙质河床推移质输沙率计算研究

Sandy bed-load transport

沙质河床推移质输沙计算无论在河流动力学的基本理论研究,还是在工程应用方面都有重要意义。本文回顾了前人主要研究成果,认为因推移质输沙率测验精度低而使现有公式多不适用于典型沙质河床,故在阐明推移质与悬移质泥沙交换运动机理基础上,借助因测验精度较高而在学科研究较成熟的悬移质含沙量垂线分布公式,通过向河底外延推求出推移质泥沙输沙率,并充分考虑泥沙粒径、水流强度及水力摩阻特性对沙质推移质输沙厚度的影响,得到了物理概念清晰、形式较为简明的沙质推移质输沙率公式。通过黄河细沙河床实测资料验证结果表明,本文建立的公式比前人推移质输沙率公式具有较高计算精度,可以应用到推移质输沙率测验精度不能保证的沙质河段的河床变形计算。

Calculation of bed-load transport is the key for both the research of sandy bed deformation andthe engineering application. Based on the review of representative formulae used in China, it is realizedthat most of the existing bed-load transport formulae are not suitable for sandy riverbed because the accura-cy of the measured data cannot be guaranteed. This paper addresses the exchange mechanism of bed-loadand suspended sediment at riverbed layer;then recurs to sediment concentration vertical distribution formu-la extended to the riverbed, considering the impact of sediment particle size, flow intensity and hydraulicfriction characteristics on the sandy bed-load transport intensity. Finally, a high reliability sandy bed-loadtransport rate formula has been derived. It shows that the measured data of natural sandy riverbed agreewell with calculation and the formula can be used in the natural engineering calculation.