长江口深水航道三维水动力与盐度数值模拟研究

发布时间：2018-03-25 13:29

本文选题：长江口深水航道　切入点：导堤-丁坝模块　出处：《天津大学》2014年硕士论文

【摘要】：本文利用FVCOM模型建立了长江口深水航道三维水动力、盐度数值模型，对深水航道整治工程不同阶段的水流、盐度运动规律进行模拟研究，并结合实测资料对近底泥沙运动和航槽淤积进行了分析。本文具体研究内容和结论如下： 1、采用FVCOM中的导堤-丁坝模块，对上挑形淹没丁坝附近的水流进行数值模拟，并与已有物理模型试验观测到的自由水面线和流速分布资料进行了比较。结果表明，模型能够合理描述潜堤顶部过水现象，反映潜堤附近三维环流特征。 2、为了方便快捷地建立长江口深水航道工程地形系统，建立了专门用于寻找潜堤节点及单元对应关系的算法，优化了大型工程项目中对于窄堤算法的运用。收集大量实测地形资料，并对测量资料进行基面转换统一到黄海基面，建立了长江口深水航道不同工期的地形。 3、利用2012年洪季长江口实测潮位、流速流向、盐度资料对所建立的数学模型进行合理性验证，验证结果表明，本文所建立的FVCOM数学模型能够较好的反映长江口水动力、盐度场变化规律。 4、深水航道整治工程不同阶段的水动力模拟结果表明，长江口深水航道工程整治建筑物区间内存在大量平面环流与垂向环流，航道两侧的近底横流现象比较明显，，这些复杂的水流运动有利于浅滩泥沙进入航槽沉积。。 5、不同工况的流线分析与质点追踪结果表明，新浏河潜堤工程的建设可能使三期工程后南北槽分流口处落潮流向南偏转，北槽落潮的分流比有所减小，而且分流比减小与新浏河潜堤工程南沙头通道限流段高程偏高有一定关系。 6、采用2012年洪季水位和流量边界条件，分别模拟一期，二期，三期不同工况时长江口深水航道工程的盐度场，分别从盐度的全场变化和南北槽的局部变化，深水航道沿程垂向盐度等方面分析了从一期到三期的盐度变化趋势。 7、结合实测近底悬沙数据，进一步推算长江口深水航道内泥沙近底分布情况，并对深水航道拐弯段近底泥沙运动进行了计算及分析。计算结果表明，三期工况下洪季期间（5月~9月），拐弯段内由两侧浅滩进入航槽内的泥沙量按疏浚密度1690kg/m3折合高达3200万方，是造成长江口深水航道淤积严重的重要原因。
[Abstract]:In this paper, the three-dimensional hydrodynamic and salinity numerical model of the Yangtze Estuary deepwater channel is established by using the FVCOM model. The flow and salinity movement in different stages of the deepwater channel regulation project are simulated and studied. Combined with the measured data, the near bottom sediment movement and the sediment deposition in the channel are analyzed. The specific contents and conclusions of this paper are as follows:. 1. A numerical simulation of the flow near the submerged spur dike with the guide dike and dike module in FVCOM is carried out, and it is compared with the free water surface profile and the velocity distribution data observed in the physical model test. The model can reasonably describe the overflowing phenomenon at the top of the submersible embankment and reflect the three-dimensional circulation characteristics near the submerged embankment. 2. In order to establish the topographic system of the Yangtze Estuary deepwater channel project conveniently and quickly, an algorithm for finding the corresponding relationship between the node and the unit of the submersible embankment is established. This paper optimizes the application of narrow embankment algorithm in large engineering projects, collects a large number of measured topographic data, and unifies the surveying data to Huang Hai's base surface, and establishes the topography of the Yangtze Estuary deepwater channel during different periods. 3. Using the measured tidal level, velocity direction and salinity data in the Changjiang Estuary in the flood season of 2012, the established mathematical model is verified. The results show that the FVCOM mathematical model established in this paper can reflect the hydrodynamic force of the Changjiang Estuary well. Variation of salinity field. 4. The hydrodynamic simulation results at different stages of the regulation project of deep water channel show that there are a large number of plane circulation and vertical circulation in the regulation building section of Yangtze Estuary deepwater channel engineering, and the phenomenon of near bottom cross flow on both sides of the channel is obvious. These complex flow movements facilitate the shoal sediment to enter the channel sediment. 5. The results of streamline analysis and particle tracing under different working conditions indicate that the construction of the new Liuhe submersible embankment project may make the downtrend of the north and south channels deflect to the south after the third phase of the project, and the shunt ratio of the north trough to the tide will be reduced. And the decrease of the diversion ratio is related to the high elevation of the limited section of Nansha Tou channel of Xinliuhe submersible embankment project. 6. Using the boundary conditions of water level and discharge in the flood season of 2012, the salinity field of the Yangtze Estuary Deepwater Channel Project is simulated in the first, second and third stages, respectively, from the full field of salinity to the local variation of the north and south channels. The variation trend of salinity is analyzed from the first stage to the third period in the vertical salinity along the deep water channel. 7. Based on the measured data of near-bottom suspended sediment, the distribution of sediment near bottom in the deep channel of the Yangtze Estuary is further calculated, and the near bottom sediment movement in the bend section of the deep water channel is calculated and analyzed. The results show that, During the period of flood season (May ~ September), the amount of sediment entering the channel from both sides of shoal in the bend section according to the dredged density 1690kg/m3 is as high as 3200 square, which is the important reason for the serious siltation of deep water channel in the Changjiang Estuary.
【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】：U612

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