强不平衡输沙含沙量与粒配垂线分布规律研究

The relationship between Longitudinal transport state and Vertical distribution characteristics of sedimentation in a river is one of mutual interdependence.The vertical distribution law of sediment concentration and suspended sediment size fractions in strongly nonequilibrium sediment transport is a core in the nonequilibrium sediment transport theory. It advances slowly due to constraints of scientific and technological developments and data measured, which has become the bottleneck of the theory of nonequilibrium sediment transport. To start the research involved in the development of river sediment disciplines'key points,and has an important significance in promoting the development of discipline and great applied value to engineering practice. By measuring the data accurately and systematically of vertical distributions of sediment concentration and suspended sediment size fractions of uniform sediment and non-uniform sediment in the states, such as sub-saturation with no bed material recharged and fully recharged, equilibrium, supersaturation and sub-saturation with bed material fully recharged, in runs of experiments, On the basis of summing up the existing achievement systematically , the project intends to not only reconstruct theoretical system of vertical distribution of sediment concentration and suspended sediment size fractions under strongly non-equilibrium sediment transport to reveal mechanisms for vertical distribution adjustment when suspended sediment changes from equilibrium to nonequilibrium, mechanisms for differences formed between vertical distributions of uniform and non-uniform sediment concentration for the same average diameter, and independence mechanism of nonuniform sediment between vertical distribution of suspended load gradation and vertical distribution of sediment concentration , but also establish theoretical formula of vertical distribution of sediment concentration and suspended sediment size fractions under strongly nonequilibrium sediment transport by constructing relevant parameters and their expressions.

河流中泥沙纵向输沙状态与垂线分布特性是相互依存的。强不平衡输沙含沙量与粒配垂线分布规律是不平衡输沙理论的核心内容之一。受基础理论工具与测验技术的限制，该问题研究进展缓慢，已成为不平衡输沙理论发展的瓶颈。开展该项研究触及河流泥沙学科发展中的关键难点，对推进学科的发展具有重要意义，在工程实践中也具有巨大的应用价值。 本项目拟通过多组水槽试验，系统而精确地测量均匀沙与非均匀沙在次饱和输沙无床沙补给、平衡输沙、超饱和输沙、次饱和输沙床沙充分补给等状态下的含沙量与粒配垂线分布；在系统总结已有成果的基础上，重构强不平衡输沙含沙量与粒配垂线分布理论体系，揭示悬沙由平衡输沙向不平衡输沙转化时含沙量垂线分布调整机理、相同平均粒径的均匀沙与非均匀沙含沙量垂线分布差异形成机理、非均匀沙悬沙粒配垂线分布与含沙量垂线分布依存机制等；构造相关物理参数及其表达式，建立强不平衡输沙含沙量与粒配垂线分布理论公式。

河流中泥沙纵向输沙状态与垂线分布特性是相互依存的。强不平衡输沙含沙量与粒配垂线分布规律是不平衡输沙理论的核心内容之一。挟沙水流在运行过程中，不仅河床发生冲淤变化，而且悬移质泥沙同床沙（或推移质）时刻进行着不同程度的交换，结果使悬沙和床沙组成不断调整。.本项目在床沙与悬沙交换理论研究的基础上，首先开展了高含沙水体泥沙群体沉降试验，而后通过多组水槽试验，系统而精确地测量均匀沙与非均匀沙在次饱和输沙无床沙补给、平衡输沙、超饱和输沙、次饱和输沙床沙充分补给等状态下的含沙量与粒配垂线分布。试验结果表明：.①通过理论研究，创建了冲淤物粒径概念，建立了多沙河流床沙与悬沙交换一维、二维、三维方程，并理论探讨了冲淤物粒径计算公式，提出了含沙量沿垂线分布与粒径的垂线分布理论依据关系，提出了不同粒径泥沙垂线分布差异的形成机理。.②通过泥沙沉降试验，建立了泥沙群体沉速与含沙量的相对关系曲线，提出含沙量对沉速的影响机制。.③通过非饱和输沙状态下含沙量沿垂线分布试验发现，河道输沙状态由平衡转向非平衡时，其含沙量沿垂线分布首先作出调整，基本表现为，由平衡状态向超饱和状态转变时，含沙量沿垂线分布较平衡状态更为均匀，向次饱和转化时变的更不均匀；在冲刷条件下，床沙有补给时，含沙量沿垂线分布比无补给情况更为均匀；相同平均粒径的均匀沙含沙量沿垂线分布比非均匀沙更为均匀。通过上述试验研究，揭示了泥沙非均匀性对含沙量垂线分布的影响机理、非均匀沙悬沙粒配垂线分布与含沙量垂线分布的依存机制，以及输沙由平衡转向不平衡时含沙量垂线分布的调整机理。