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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
The theoretical analysis shows that the fine particles entrained in the water flow are not only related to the particle size and the flow of water but also to the concentration of fine particles in the sand and sediment of the river basin.By analyzing the concentration distribution of fine particles near the bed surface, The fine particles can exist in a large amount in the water flow, but the conditions that do not participate in the formation of the bed are that the concentration of fine particles in the upper stream is smaller than that of the water flow. The essential reason is that the relative intensity of the water flow is large enough, The lift on the fine particles is larger than the particle floats, making the concentration of fine particles rapidly approaching zero from the top to the bottom of the bed and has a positive concentration gradient.In this paper, Bed sandy and bed sandy three, and made a quantitative definition, clarified some of the conceptual chaos