水流的冲泻质输沙机理研究Ⅰ：理论分析

本文理论分析表明，水流挟带的细颗粒是否参与造床，不仅与颗粒大小、水流强弱有关，而且与流域来沙中细颗粒浓度密切相关。通过分析细颗粒在床面附近浓度分布，发现细颗粒能够在水流中大量存在，但不参与造床的条件为上游来沙中细颗粒浓度小于水流的最大冲泻质输沙能力；其本质原因是水流相对强度足够大，床面附近作用在细颗粒上的升力大于颗粒浮重，使得细颗粒浓度在床面附近自上向下迅速趋近于零而具有正的浓度梯度。文中将水流输运泥沙区分为冲泻质、冲泻型床沙质和床沙质三种，并作出了定量定义，澄清了一些概念上的混乱。

Wash load transport in alluvial river Ⅰ:Theory

Theoretical analysis shows that the fine material transported as wash load is not only determined by flow intensity and particle size, but also strongly influenced by its concentration. It is demonstrated in this paper that rivers have a maximum transport capacity for fine material at a certain flow intensity, under which fine material can keep its fraction in bed load composition as zero. Otherwise, it behaves as bed material load. A new criterion of differentiation for wash load and bed material load is also proposed based on the theory of this paper.