床面形态对泥沙输移的影响机理及应用研究

Bed form is a very important factor that influences alluvial resistance and sediment transport.Research on the influencing mechanism,has been a difficult point.The bedform control factor theory,proposed recently abroad, can reflect basic characteristics of bedform and bedform resistance.Therefore, to be on the basis of this theory, the changing laws of typical bedforms such as dune,high stage plane,anti-dune and the corresponding sediment transport will be studied by the use of flume experiments and the existing achievements, combined with analysis of the Yellow River typical bedforms variation.The quantitative description index and quantitative discriminant method for bedforms will be established,as well as the bedform-dependent alluvial resistance formula.The method will be verified and improved with observed bedforms data in the Lower Yellow River.Further study will be on the effect and expression forms of alluvial resistance in sediment transport with Wuhan Hydropower College sediment-carrying capacity theory which is used widely.Then make futher research on the mechanism of bedform action to sediment transport.Finally, the bedform and water and sediment conditions corresponding to high efficient sediment transport in the Lower Yellow River will be proposed.This result can provide theoretical basis and technical support for the water and sediment regulation of the Yellow River.The study also can provid new ideas and methods for further research on alluvial river resistance and sediment transport capacity.

床面形态是冲积阻力、泥沙输移的重要影响因素，其影响机理的研究，一直是泥沙输移研究中的难点。近期国外提出的床面形态控制数理论，可初步反映床面形态及冲积阻力的基本特征。因此，拟在该理论的基础上，利用室内试验及已有成果，结合黄河下游典型床面形态实例分析，研究冲积河流典型床面形态如沙垄、动平床、逆行沙波的变化规律，不同床面形态相应的输沙特性；建立床面形态定量描述指标及定量判别方法，提出以床面形态指标表征的冲积阻力计算公式，利用黄河下游等实测床面形态资料对建立的方法进行检验和改进；以目前广泛应用的武汉水电学院挟沙能力理论，分析阻力在挟沙能力中的作用及表达形式，揭示床面形态对泥沙输移的作用机理。最后，研究提出黄河下游高效输沙床面形态及相应的水沙条件，为黄河调水调沙提供理论基础及技术支撑。该项研究还可为冲积河流阻力及输沙能力的进一步研究提供新的思路和方法。

床面形态是水流阻力及泥沙输移的重要影响因素。项目以黄河下游河道及上游交汇区等为研究对象，利用先进的观测设备进行了野外河流床面形态的观测，开展了黄河床面形态变化特征，床面形态表征及判别，床面形态对阻力及泥沙输移的影响等理论研究，黄河上游交汇区河床形态及冲淤规律，黄河下游高含沙洪水河床形态及冲淤调整规律等应用研究。首先，获得了黄河下游游荡型河段花园口水文站附近4km*60m范围的三维床面形态数据和图形，首次发现了黄河下游持续冲刷时期的双尺度沙垄特征，床面形态波长与波高比显著大于其他河流及室内实验，诠释了黄河下游具有较强输沙能力的原因；揭示了床面形态由沙垄-过渡-动平床的发展过程，黄河下游小流量时曼宁糙率可大于0.025的超高阻力，大流量时曼宁糙率可小于0.01的超低阻力特征，定量描述了水流阻力对床面形态变化的响应过程，并计算了黄河下游沙粒阻力；提出了床面形态表征指标及黄河下游床面形态判别关系，基于该指标计算的水流阻力较曼宁糙率更为合理且精度较高；发现了相对平衡条件下，含沙量随床面形态变化的三个阶段即由沙纹到沙垄的快速增加阶段，沙垄到过渡或动平整的相对稳定阶段，动平整床面以后的增加阶段，为提高黄河下游挟沙能力计算精度的提高提供了基础；提出了黄河上游交汇区高含沙洪水形成的河床形态的基本模式，即壅水区沙洲、分离区沙洲、输水输沙主槽及分离区下游的沙洲，建立了交汇区泥沙冲淤计算方法；描述了高含沙洪水河床形态及滩槽冲淤规律，提出了黄河下游高含沙洪水调控指标，可为黄河下游的高效输沙及防洪提供技术支持。