非恒定流作用下丁坝水沙运动及水毁特征数值模拟

发布时间：2018-04-01 12:32

本文选题：非恒定流条件　切入点：丁坝冲刷模型　出处：《重庆交通大学》2014年硕士论文

【摘要】：丁坝是山区河流最常用的航道整治建筑物，由于山区河流坡陡流急，水位变化较大，水毁现象严重，开展非恒定流条件下丁坝水毁及水沙运动仿真模拟，对于提高山区河流航道整治工程规划、设计和管理水平具有重大的理论意义和实用价值。论文重点研究了非恒定流条件下丁坝水沙运动及水毁特征的平面二维数值模拟方法，通过对比分析模拟计算结果，总结出非恒定流条件下丁坝特定的水沙运动规律，并与实际情况对比验证，保证了数值模拟研究方法的科学有效合理性。论文以泥沙运动力学、计算流体动力学等学科理论为根基，在对丁坝水毁特征进行实地考察和理论分析的基础上，结合物理模型试验成果，采用具有水、沙模拟计算功能的MIKE21软件来对非恒定流作用下的丁坝水动力和动床模型进行平面二维数值模拟仿真，探索了非恒定流条件下丁坝水流结构、泥沙冲淤的模拟方法，并取得以下研究结论： 1、在有限体积法的基础上，以三角形非结构网格为单元离散划分的平面二维浅水方程与河床变形方程模型在计算非恒定流条件下的丁坝水沙运动时稳定可靠，该研究方法能够为相应物理模型实验和理论分析提供支撑。 2、试验证明与MIKE软件传统的剖分计算方法相比,用SMS软件可以对模型网格进行优化，使网格剖分质量更好，模型计算更稳定；以特定文件为接口使SMS与MIKE相结合的模拟方法可行有效，，比传统MIKE模拟方法可以更好的模拟出水槽丁坝地形及其水沙运动特性。 3、非恒定流条件下的丁坝水流运动有其特殊规律：全流场范围内大流速主要集中在坝顶和丁坝下游主流区两处位置；坝前流速沿坝轴方向从0开始逐渐增大，在坝长范围内近似线性分布；丁坝附近水流动力轴线上流速呈现先增大后减小的变化规律，最大值位于距离丁坝一定范围内的下游；坝后回流区的产生位置恰好与丁坝下游大流速范围横向对应。 4、在非恒定流作用下，丁坝下游流场与水位呈现特殊关系，大流速的位置水位较高，回流区流速小反而水位较低，最低点在回流的漩涡中心。 5、非恒定来流对丁坝模型造成的冲刷主要包括：冲刷坑、淤积沙垄、坝头冲刷、坝身塌陷和坝后冲刷5个特点。大洪峰流量造成的河床变形是发生丁坝水毁的重要成因。
[Abstract]:The spur dike is the most commonly used waterway regulation building in mountainous rivers. Due to the steep flow of mountain rivers, the change of water level is large and the phenomenon of water destruction is serious, the simulation simulation of the water damage and the movement of water and sediment under the condition of unsteady flow is carried out. It is of great theoretical significance and practical value to improve the planning, design and management level of river channel regulation engineering in mountainous areas. This paper focuses on the planar two-dimensional numerical simulation method for the characteristics of water and sediment movement and water destruction of spur dams under the condition of unsteady flow. By comparing and analyzing the simulation results, the specific water and sediment movement laws of groin under unsteady flow conditions are summarized, and compared with the actual conditions, the scientific and effective rationality of the numerical simulation research method is guaranteed. Based on the theories of sediment movement mechanics, computational fluid dynamics and so on, on the basis of field investigation and theoretical analysis of the characteristics of water destruction of spur dikes, combined with the results of physical model tests, the paper adopts water. The MIKE21 software of sand simulation function is used to simulate the hydrodynamic force and moving bed model of spur dike under unsteady flow, and the simulation method of water structure and sediment scour and deposition under unsteady flow is explored. The following conclusions are obtained:. 1. On the basis of the finite volume method, the plane two-dimensional shallow water equation and the riverbed deformation equation model, which are discretized by triangular unstructured meshes, are stable and reliable in the calculation of the hydro-sediment movement of the groin under the condition of unsteady flow. The research method can provide support for the corresponding physical model experiments and theoretical analysis. 2. Compared with the traditional method of MIKE software, the model mesh can be optimized by using SMS software, so that the mesh generation quality is better and the model calculation is more stable. It is feasible and effective to combine SMS and MIKE with special file interface. Compared with the traditional MIKE simulation method, it can better simulate the groin topography and the characteristics of water and sediment movement. 3. Under the condition of unsteady flow, the flow movement of spur dike has its special law: in the whole flow field, the large velocity is mainly concentrated at the top of the dam and the downstream of the dike, and the velocity in front of the dam increases gradually along the direction of the axis of the dam. The velocity in the hydrodynamic axis near the spur dike increases first and then decreases, and the maximum value is located downstream from the dike in a certain range. The location of the backflow zone is exactly corresponding to the large velocity range of the lower reaches of the spur dike. 4. Under the action of unsteady flow, the downstream flow field of the spur dike has a special relationship with the water level. The position of the large velocity of velocity is higher, but the water level of the backflow zone is lower, and the lowest point is in the center of the swirl of the return current. 5. The erosion caused by unsteady flow mainly includes: scour pit, silt ridge, dam head scour, dam body collapse and dam back scour. The river bed deformation caused by great Hong Feng discharge is the important cause of dike water destruction.
【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】：U617.91;U612.23

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