四面六边透水框架群防护桥墩局部冲刷的数值模拟
发布时间：2018-11-18 09:43
【摘要】：冲积性河流中,桥梁的水害尤其是桥墩的局部冲刷几乎不可避免。局部冲刷这种桥墩附近局部河床床面的下切现象,通常是由桥墩周围水流的三维边界层分离所产生的高强度的水流紊动和旋涡体系所引起的,关系到桥梁基础的稳定。因此,桥梁设计工作者在进行桥梁基础设计时,必须考虑采取一些防护工程对桥墩周围的床面进行护底防护,以保证桥墩的安全与稳定。迄今为止,桥墩局部冲刷的防护工程一直是防止河槽中桥墩周围床面冲刷、桥墩失稳和桥梁水毁的重要措施之一。现有的桥墩局部冲刷防护工程措施都存在一些缺点和不足,在一定条件下,这些缺点和不足甚至会引发整个防护工程的溃败,进而影响桥墩的稳定和桥梁的安全运行。在护岸工程和堤防工程中表现突出的四面六边透水框架群防护方法被提出用作桥墩局部冲刷的防护,成为一项新型的桥墩局部冲刷防护措施。科学技术高速发展的今天,计算机技术的进步给计算流体力学的发展带来了契机,复杂紊流场通过计算流体力学软件进行模拟的成果已逐渐得到行业认可。运用计算流体力学对四面六边透水框架群的桥墩局部冲刷防护效果进行模拟研究将是不同于以往传统的冲刷防护研究的方向。本文在研究掌握桥梁水害形成原因的基本性质基础上,针对桥墩冲刷这一桥梁水害的最重要反映形式,深刻分析其产生机理,从水流结构上认识桥墩局部冲刷的形成过程;掌握数值模拟中与桥墩局部冲刷相关的控制方程和封闭方法,以及离散和边界控制办法等具体技术手段,然后对桥墩局部冲刷的四面六边透水框架群防护数值模拟从以下方向展开:(1)对单个桥墩冲刷防护的研究。结合文献中物理模型资料,在单墩周围布设四面六边透水框架群,建立三维数学概化模型,以非结构化网格划分方法,采用Fluent软件进行数值模拟,观察分析模拟出来的水流流场和水流结构情况。重点分析了四面六边透水框架对形成局部冲刷的水流结构以及水流速度的影响。(2)对群桩基础冲刷防护的研究。结合包西铁路大桥群桩基础的实体尺寸,在其周围布设四面六边透水框架群,同样建立三维数学模型进行数值模拟,以流速为切入口分析四面六边透水框架群对群桩基础的防护效果。然后结合研究者对透水框架的理论探讨和透水框架抛投防护在护岸护滩工程中的实际应用经验,给包西铁路大桥群桩基础的具体防护提出了合理防护建议。
[Abstract]:In alluvial rivers, the water damage of bridges, especially the local erosion of piers, is almost inevitable. The local scouring of the local riverbed surface near the pier is usually caused by the high intensity turbulent flow and vortex system caused by the separation of the three-dimensional boundary layer of the flow around the pier, which is related to the stability of the bridge foundation. Therefore, in order to ensure the safety and stability of the bridge pier, the bridge designer must take some protective works to protect the bed floor around the pier in order to ensure the safety and stability of the bridge pier. Up to now, the protection of local erosion of bridge piers has been one of the important measures to prevent the erosion of the bed surface around the pier, the instability of the pier and the damage of the bridge water in the channel. The existing measures for partial scour protection of bridge piers all have some shortcomings and shortcomings. Under certain conditions, these shortcomings and deficiencies may even lead to the collapse of the whole protection project, thus affecting the stability of the pier and the safe operation of the bridge. The four-sided and six-sided permeable frame group protection method, which is outstanding in bank protection and embankment engineering, has been proposed as a local scour protection for bridge piers, which has become a new protection measure for local scour of bridge piers. With the rapid development of science and technology, the development of computer technology has brought opportunities to the development of computational fluid dynamics. The results of complex turbulence field simulation by computational fluid dynamics software have been gradually recognized by the industry. Using computational fluid dynamics to simulate the local scour protection effect of bridge piers in the four-sided and six-sided permeable frame group will be different from the traditional research on scour protection. On the basis of studying and mastering the basic properties of the formation of bridge water hazard, aiming at the most important reflection form of bridge pier scour, this paper deeply analyzes its producing mechanism, and understands the formation process of local scour of bridge pier from the point of view of water flow structure. Mastering the control equations and closing methods related to local scour of bridge piers in numerical simulation, as well as concrete technical means such as discrete and boundary control methods, etc. Then the numerical simulation of four-sided and hexagonal permeable frame group protection is carried out from the following directions: (1) the study on the scour protection of single pier. Combined with the physical model data in the literature, a three-dimensional mathematical generalization model was established by placing a four-sided and six-sided permeable frame group around a single pier, and the numerical simulation was carried out by using Fluent software, using the unstructured meshing method. The simulated flow field and flow structure are observed and analyzed. The influence of the six-sided permeable frame on the formation of the local scour flow structure and the flow velocity is analyzed. (2) the study on the erosion protection of pile group foundation. Combined with the solid dimension of pile group foundation of Baoxi Railway Bridge, a four-sided and six-sided permeable frame group is arranged around it, and a three-dimensional mathematical model is also established to carry out numerical simulation. This paper analyzes the protective effect of four-sided and six-sided permeable frame group on pile group foundation with the velocity of velocity as the entrance. Then, based on the theoretical discussion of the permeable frame and the practical application experience of the throwing and throwing protection of the permeable frame in the bank and beach protection project, some reasonable protection suggestions are put forward for the concrete protection of the pile foundation of Baoxi Railway Bridge.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U442.32
本文编号：2339688
[Abstract]:In alluvial rivers, the water damage of bridges, especially the local erosion of piers, is almost inevitable. The local scouring of the local riverbed surface near the pier is usually caused by the high intensity turbulent flow and vortex system caused by the separation of the three-dimensional boundary layer of the flow around the pier, which is related to the stability of the bridge foundation. Therefore, in order to ensure the safety and stability of the bridge pier, the bridge designer must take some protective works to protect the bed floor around the pier in order to ensure the safety and stability of the bridge pier. Up to now, the protection of local erosion of bridge piers has been one of the important measures to prevent the erosion of the bed surface around the pier, the instability of the pier and the damage of the bridge water in the channel. The existing measures for partial scour protection of bridge piers all have some shortcomings and shortcomings. Under certain conditions, these shortcomings and deficiencies may even lead to the collapse of the whole protection project, thus affecting the stability of the pier and the safe operation of the bridge. The four-sided and six-sided permeable frame group protection method, which is outstanding in bank protection and embankment engineering, has been proposed as a local scour protection for bridge piers, which has become a new protection measure for local scour of bridge piers. With the rapid development of science and technology, the development of computer technology has brought opportunities to the development of computational fluid dynamics. The results of complex turbulence field simulation by computational fluid dynamics software have been gradually recognized by the industry. Using computational fluid dynamics to simulate the local scour protection effect of bridge piers in the four-sided and six-sided permeable frame group will be different from the traditional research on scour protection. On the basis of studying and mastering the basic properties of the formation of bridge water hazard, aiming at the most important reflection form of bridge pier scour, this paper deeply analyzes its producing mechanism, and understands the formation process of local scour of bridge pier from the point of view of water flow structure. Mastering the control equations and closing methods related to local scour of bridge piers in numerical simulation, as well as concrete technical means such as discrete and boundary control methods, etc. Then the numerical simulation of four-sided and hexagonal permeable frame group protection is carried out from the following directions: (1) the study on the scour protection of single pier. Combined with the physical model data in the literature, a three-dimensional mathematical generalization model was established by placing a four-sided and six-sided permeable frame group around a single pier, and the numerical simulation was carried out by using Fluent software, using the unstructured meshing method. The simulated flow field and flow structure are observed and analyzed. The influence of the six-sided permeable frame on the formation of the local scour flow structure and the flow velocity is analyzed. (2) the study on the erosion protection of pile group foundation. Combined with the solid dimension of pile group foundation of Baoxi Railway Bridge, a four-sided and six-sided permeable frame group is arranged around it, and a three-dimensional mathematical model is also established to carry out numerical simulation. This paper analyzes the protective effect of four-sided and six-sided permeable frame group on pile group foundation with the velocity of velocity as the entrance. Then, based on the theoretical discussion of the permeable frame and the practical application experience of the throwing and throwing protection of the permeable frame in the bank and beach protection project, some reasonable protection suggestions are put forward for the concrete protection of the pile foundation of Baoxi Railway Bridge.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U442.32
【引证文献】
相关硕士学位论文 前1条
1 储昊;透空四面体扰流机理及冷连接加工方法[D];重庆交通大学;2016年
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