长江口泥沙运动及深水航道淤积数值模拟研究

发布时间：2018-02-03 03:01

本文关键词： 长江口深水航道工程 FVCOM模型粘性泥沙沉速公式盐度层化　出处：《天津大学》2014年硕士论文　论文类型：学位论文

【摘要】：长江口深水航道工程自建设以来已经发挥了巨大经济效益和社会效益,但同时也面临着航道回淤量较大、回淤位置比较集中的问题。为了研究长江口深水航道泥沙运动规律,探索航道回淤原因,本文基于FVCOM三维水动力、盐度、悬沙数学模型和平面二维浮泥模型建立了长江口深水航道工程海域的水-沙-盐度数学模型,对深水航道工程区域的泥沙运动规律和航道淤积机理就行了研究。本文的具体研究内容和主要结论如下:(1)提出了综合考虑温度、粒径、含沙量、盐度、紊动强度对絮凝影响的粘性泥沙沉速公式,并结合现场观测及实验数据确定公式中部分参数,得到了适用于长江口深水航道工程的泥沙沉速公式,公式计算得到的沉速范围与前人研究结果基本一致。(2)根据建立的长江口深水航道工程三维水动力、盐度、泥沙数学模型模拟结果,研究并分析了盐度层化效应对长江口附近海域水动力和悬沙垂向分布的影响,结果表明考虑盐度层化效应后,密度层化产生的紊动抑制使得垂向紊动粘性减小,表层流速变大,底层流速变小,流速垂向平均值变大,悬沙分层更为明显,表层含沙量变小,底层含沙量变大,考虑层化效应的速度和含沙量分布与实测值更为吻合。层化效应对长江口水动力和泥沙运动有重要影响。(3)对本文所建立的三维数学模型进行验证,含沙量、水沙通量以及淤积结果均与实测值吻合良好,表明本文所建立三维泥沙数学模型能较好地反映长江口深水航道工程附近海域的水流、泥沙运动特性。在此基础上,分析了悬沙以及浮泥的运动规律,结果表明,由边滩进入航道的浮泥是深水航道淤积的最重要来源。
[Abstract]:The Yangtze Estuary deepwater channel project has played a great economic and social benefit since its construction, but at the same time it is also faced with the problem of large amount of channel siltation and relatively concentrated siltation position. In order to study the regulation of sediment movement in the deep water channel of the Yangtze River Estuary, In this paper, based on FVCOM three-dimensional hydrodynamic model, salinity model, suspended sediment mathematical model and planar two-dimensional sediment model, the water-sediment salinity mathematical model of the Yangtze Estuary deepwater waterway engineering sea area is established. The regularity of sediment movement and siltation mechanism in deep water channel engineering area are studied. The concrete contents and main conclusions of this paper are as follows: 1) the temperature, particle size, sediment content and salinity are considered synthetically. The formula of settling velocity of viscous sediment, which influences the effect of turbulence intensity on flocculation, is obtained by combining with field observation and experimental data to determine some parameters of the formula, which is suitable for the deep-water channel engineering of the Yangtze River Estuary. The range of settling velocity calculated by the formula is basically consistent with the previous research results. (2) according to the mathematical model of hydrodynamic force, salinity and sediment of the Yangtze Estuary Deepwater Channel, The effect of salinity stratification on the hydrodynamic and suspended sediment vertical distribution in the sea area near the Changjiang Estuary is studied and analyzed. The results show that the turbulence suppression caused by density stratification reduces the vertical turbulent viscosity and increases the surface velocity after considering the salinity stratification effect. The velocity of the bottom layer becomes smaller, the vertical average velocity of velocity increases, the stratification of suspended sediment becomes more obvious, the sediment content of the surface layer becomes smaller, and the sediment content of the bottom layer becomes larger. Considering the velocity and sediment concentration distribution of stratification effect, it is more consistent with the measured value. The stratification effect has an important influence on hydrodynamic and sediment movement in the Changjiang Estuary. The results of water and sediment fluxes and siltation are in good agreement with the measured values, which indicates that the 3D sediment mathematical model established in this paper can well reflect the characteristics of water flow and sediment movement in the waters near the Yangtze Estuary Deepwater Channel Project. The movement law of suspended sediment and floating mud is analyzed. The results show that the sediment entering the channel from the banks is the most important source of sediment deposition in the deep water channel.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV148

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