弯道水流结构及泥沙输移过程研究

发布时间：2018-06-12 12:16

本文选题：弯曲河流 + 非均匀沙起动　；参考：《天津大学》2014年博士论文

【摘要】：本文以弯曲型河流为研究对象，基于韩其为的泥沙运动统计理论体系，结合模型试验的方法，研究了水流的结构特性及泥沙输移过程。在充分考虑非均匀沙的起动低输沙率、暴露度以及弯道的水力结构导致的水面横比降、环流影响的基础上，对斜坡、弯道凹岸边壁上的泥沙建立了较清晰的物理图形，并较全面分析了各种力的作用，采用滚动平衡方式推导了斜坡、弯道凹岸边壁上泥沙起动流速公式，所得弯道凹岸边壁上泥沙起动流速公式适用于粗、细颗粒，，并且概括性高，可以简化为顺直河流边壁泥沙起动，以及床面泥沙起动。基于韩其为的泥沙运动统计理论体系，将转移概率作为理论基础，充分考虑了紊流猝发对床面颗粒起悬周期的影响，对非均匀沙的参考面平衡浓度公式进行了推导。采用物理模型试验的方法，对理想弯道的水流运动规律进行了研究。其中包括水流动力轴线、纵向流速、横向流速、垂向流速的垂线分布，环流强度及其环流结构等试验数据的时均值分析；以及紊动强度、雷诺切应力、紊流猝发等试验数据的脉动值分析。采用自然模型试验的方法，在提前塑造好的初始顺直河槽中进行模型试验，通过改变流量、初始河宽、入射角等研究河流演变过程和形成机理，采用粒子跟踪技术（PTV）来进行流速测量。本文的四组试验比较好的反映了河流演变的过程，前三组研究河流成型以及从试验现象、试验后的地形、河流的平面形态等方面定性分析河流的演变过程，第四组试验主要研究弯曲河流的演变过程。试验成功塑造出顺直河流、分汊河流、弯曲河流，在试验过程中出现了浅滩、边滩、江心洲、裁弯取直等典型的试验现象。通过对试验结果分析得出江心洲形成过程、弯曲河流形成过程以及流量对于河型的影响等基本结论。
[Abstract]:In this paper, the structure characteristics and sediment transport process of river flow are studied based on the statistical theory system of sediment movement based on Hanqi River and the method of model test. On the basis of fully considering the effect of incipient low sediment transport rate, exposure degree and hydraulic structure of curved channel on water surface transverse ratio drop and circulation, a clear physical figure of sediment on slope and concave bank wall is established. The effect of various forces is comprehensively analyzed, and the formula of sediment starting velocity on slope and concave bank wall is derived by rolling balance method. The obtained formula is suitable for coarse, fine particles and high generality. It can be simplified as the sediment incipient on the side wall of the straight river and the sediment incipient on the bed surface. Based on the statistical theory system of sediment movement, the transfer probability is taken as the theoretical basis, and the influence of turbulent burst on the suspended period of bed surface particles is fully considered, and the equilibrium concentration formula of reference surface of non-uniform sediment is deduced. In this paper, the law of flow motion in ideal bend is studied by using physical model test method. It includes the time-mean analysis of the experimental data such as the axis of the flow power, the longitudinal velocity, the transverse velocity, the vertical velocity, the circulation intensity and the circulation structure, and the turbulence intensity, the Reynolds shear stress, etc. Analysis of pulsation value of turbulent burst and other test data. The natural model test method is used to study the evolution process and formation mechanism of the river by changing the flow rate, the initial river width, the incident angle, and so on. Particle tracking technique (PTV) is used to measure velocity. The four groups of experiments in this paper reflect the process of river evolution very well. The first three groups study river formation and qualitatively analyze the evolution process of river from the aspects of experimental phenomenon, topography after experiment, plane shape of river, etc. The fourth group mainly studies the evolution of curved rivers. The experiment successfully molded the straight river, the branching river flow and the curved river. During the test process, the typical experimental phenomena such as shoals, banks, Jiangxinzhou, cutting and bending straightening and so on were found. Through the analysis of the experimental results, the basic conclusions such as the formation process of Jiangxinzhou, the forming process of curved river and the influence of discharge on the river pattern are obtained.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TV143

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