电站清水下泄对下游港区水位影响数值模拟研究

发布时间：2018-03-27 07:51

本文选题：清水下泄　切入点：数学模型　出处：《重庆交通大学》2014年硕士论文

【摘要】：水利工程建成后可大幅改善库区航道尺度、通航条件以及增加和调节下游枯水流量等。但是，水利枢纽工程建成后，大坝拦截了上游输入的大量水体和泥沙，改变了河流天然的来水来沙过程，打破了河床自然的平衡型态，导致河床发生新的冲淤变形，直至达到新的冲淤平衡。此外，，水电站调峰运行产生的非恒定流，将引发下游航道中水位和流速的瞬间变化，对船舶通航条件带来较大影响。水库运行中下泄的清水因挟沙能力增强，将加快下游河槽的冲刷，使河床下切、水位降低，产生航道水深不足等问题，对下游的航道尺度、沿江港口码头及水工建筑物的正常运行带来影响。因此研究电站清水下泄给下游港区停泊水位带来的影响十分必要。本文结合“橄榄坝电站清水下泄对曼厅大沙坝航道稳定影响研究”项目，在平面二维水流泥沙数学模型的理论和方法基础上进行实际应用，主要工作和成果如下： ①依据收集的原型资料，设计和制作变态动床物理模型，通过所建物理模型进行水流流态、水位及河床冲淤测量。为数学模型的验证奠定基础。 ②建立曼厅的二维水沙数学模型，根据模拟成果与物理模型试验结果比较分析，结果表明模拟计算值与实测值吻合较好，说明建立的模型与数值模拟方法的有效性和正确性，可用于实际河道的水流和泥沙的冲淤变化的研究分析，且能够保证计算的精度和可靠性。 ③以两种不同的电站下泄流量过程为计算工况，对电站下游港区内的水流水力特性进行分析研究。通过分析年际流速大小及年流速差值得到港区内流速的变化趋势；通过电站下泄的年过程流量分析港区内水位日变幅，通过橄榄坝水库设计的下泄水流分析港区内水位小时变幅，得到满足船舶安全停泊的结论。 ④通过计算港区水位下降量及下游河床平均下切量，得到平均河床下切量与时间的关系式： h河床ln(0.077t0.988)；河床下切与港区水位的之间的关系式： h水位0.8662h河床；对满足港区特征水位的流量进行研究，得到最小流量变化与时间的关系式： Q121.36ln(x4.33)379.77，，为电站运行的流量调节提供了理论参考。
[Abstract]:After the completion of the water conservancy project, the waterway scale of the reservoir area can be greatly improved, the navigation conditions and the downstream low water flow can be increased and adjusted. However, after the completion of the water conservancy project, the dam intercepts a large amount of water and sediment input from the upstream. It changes the natural process of water and sediment coming from the river, breaks the natural equilibrium of river bed, and results in new erosion and deposition deformation of river bed until a new balance of scour and silt is reached. In addition, the unsteady flow produced by peak shaving operation of hydropower station, It will cause the instantaneous change of the water level and velocity in the downstream waterway, and will have a great influence on the navigation conditions of the ship. Due to the enhancement of the sediment carrying capacity of the clear water discharged down the reservoir, the scouring of the downstream channel will be accelerated, the river bed will be cut down and the water level will be lowered. Some problems such as insufficient water depth of waterway have an impact on the channel scale along the river and the normal operation of the port and hydraulic structures along the Yangtze River, so it is necessary to study the effect of the water discharge of the power station on the berthing water level in the downstream port area. Combined with the project of "study on the influence of clear Water discharge on the Channel Stability of Manting Dasha Dam", this paper carries out practical application on the basis of the theory and method of planar two-dimensional flow and sediment mathematical model. The main work and results are as follows:. 1 according to the prototype data collected, the physical model of abnormal moving bed is designed and made, and the water flow, water level and river bed scour and deposition are measured through the established physical model, which lays a foundation for the verification of mathematical model. (2) the two-dimensional mathematical model of water and sediment in Manting is established, and the results of simulation and physical model test are compared and analyzed. The results show that the calculated values are in good agreement with the measured values, which shows the validity and correctness of the established model and numerical simulation method. It can be used to study and analyze the flow and sediment scour and silt change of real river, and can guarantee the accuracy and reliability of calculation. (3) the hydraulic characteristics of water flow in the downstream port area of the power station are analyzed and studied under the calculation conditions of two different discharge processes of the power station. The variation trend of the velocity in the port area is obtained by analyzing the magnitude of the interannual velocity and the difference of the annual velocity. The daily variation of the water level in the port area is analyzed through the annual discharge of the power station discharge, and the hourly fluctuation of the water level in the port area is analyzed by the downflow flow designed by the Olive Dam reservoir, and the conclusion that the ship is safely berthed is obtained. (4) by calculating the water level drop in the port area and the average down-cut quantity of the downstream riverbed, the relationship between the average riverbed undercut amount and the time is obtained: h river bed lnn 0.077 t 0.988, the relationship between the river bed undercut and the port area water level: h water level 0.8662 h riverbed; The relationship between the minimum discharge change and the time is obtained: Q121.36lnX 4.33ng 379.77, which provides a theoretical reference for the regulation of the discharge of the power station.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U652.3

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