弯曲分汊河道水沙运动与河床演变耦合机理研究

发布时间：2018-08-25 18:49

【摘要】：三峡水库运用后改变了下游河道的水沙条件,下泄泥沙量大幅减少,相应水库下游弯曲分汊河道的演变过程也会作出响应,对防洪、航运、岸线利用等方面可能产生影响。因此,开展弯曲分汊河道水沙运动与河床演变耦合机理研究具有重要理论与实际意义。本文在总结了国内外已有研究成果的基础上,通过原型观测资料分析、概化模型试验与理论阐释相结合的方法,综合研究了弯曲分汊河段的水沙运动特性与河床演变规律,以及二者之间的耦合机理,预测了弯曲分汊河道的演变趋势。本文开展的主要工作与取得的主要成果如下:(1)通过原型观测资料分析与概化模型试验,研究揭示了不同水流条件下弯曲分汊河道分流区、汊道段与汇流区的水面比降、断面平均流速沿程变化、横断面流速分布、水流动力轴线、水流紊动强度及紊动能的变化规律。(2)在分析选取悬移质水流挟沙力公式与利用实测资料检验推移质输沙率公式的基础上,结合不同年份监利河段的河道地形、水沙资料和概化模型试验流速观测数据,阐明了不同水流条件下弯曲分汊河道悬移质泥沙与推移质泥沙运动规律,探讨了悬移质含沙量分布与主流分布的异位现象。(3)通过原型观测资料分析和概化模型试验,分析揭示了不同水沙条件下弯曲分汊河道总体冲淤变化规律及分流区、汊道段、汇流区的演变规律,探讨了弯曲分汊河道主支汊移位的演变模式。(4)通过弯曲分汊河道的水沙运动与河床演变之间的关联分析,揭示了二者之间的耦合机理,并以监利河段为例,预测了来沙减小条件下该河段的演变趋势。
[Abstract]:After the operation of the three Gorges Reservoir, the water and sediment conditions of the downstream channel are changed, and the amount of sediment discharged is greatly reduced, and the evolution process of the bend and branching channel in the lower reaches of the corresponding reservoir will also respond, which may have an impact on flood control, shipping and shoreline utilization and so on. Therefore, it is of great theoretical and practical significance to study the coupling mechanism between water and sediment movement and river bed evolution in the curved branching channel. On the basis of summarizing the existing research results at home and abroad, through the analysis of prototype observation data and the method of combining model test with theoretical explanation, the characteristics of water and sediment movement and the evolution law of river bed in the curved braided reach are comprehensively studied in this paper. And the coupling mechanism between them, the evolution trend of the curved branching channel is predicted. The main work and results obtained in this paper are as follows: (1) through the prototype observation data analysis and generalizable model test, the study reveals the water surface ratio of the curved branching channel to the confluence region, the water surface ratio of the branching channel to the confluence region under different water flow conditions. The mean velocity of the cross section varies along the course, the velocity distribution of the cross section, the axis of water power, (2) on the basis of analyzing the formula of sediment carrying capacity of suspended flow and testing the formula of bed load transport rate with measured data, combined with the river channel topography of Jianli reach in different years, Water and sediment data and velocity observation data of generalized model test illustrate the movement of suspended sediment and bed load sediment in curved branching channel under different flow conditions. The heterotopic phenomena of suspended sediment concentration distribution and mainstream distribution are discussed. (3) through the analysis of prototype observation data and generalizable model test, the general scour and siltation variation law of curved branching channel under different water and sediment conditions, the distributary zone and the branching section are revealed. The evolution law of confluence area is discussed, and the evolution model of main branch shift of curved branching channel is discussed. (4) through the correlation analysis between the water and sediment movement of the curved branching channel and the river bed evolution, the coupling mechanism between the two is revealed, and the Jianli reach is taken as an example. The evolution trend of the reach is predicted under the condition of sediment reduction.
【学位授予单位】：长江科学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV147

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