山区峡谷桥址处风场特性实测研究与数值模拟

发布时间：2019-05-20 04:11

【摘要】：随着西部战略的逐步实施,在中西部山区峡谷地区将有越来越多的大跨度柔性桥梁被修建,为了保证此类桥梁的顺利建造和正常的运营,准确的风荷载输入是大跨度柔性桥梁抗风设计的先决条件。但是,山区峡谷地区地势崎岖、环境复杂,风场特性各项参数很难确定,现行桥梁抗风规范中关于峡谷地形条件下的风场特性也没有详细的规定。因此,对山区峡谷风场特性的研究是非常有必要的。本文依托交通部西部课题重大专项“特大型桥梁风雨作用监测与模拟技术研究”,对澧水大桥桥位处风场特性进行了如下研究：1、在澧水大桥上建立了桥位处山区峡谷风环境的实时监测系统,对桥址峡谷风场特性进行了真实、有效的记录。分析得到了包括平均风速、风向、风速剖面、风攻角等在内的峡谷风场平均风特性以及湍流度、阵风因子、湍流功率谱密度等在内的脉动风特性。并对各项特征参数的相关性进行了拟合。澧水大桥桥位处风场受山区峡谷地形的影响,其三维特性比较显著。研究结果表明：由于澧水大桥峡谷呈弯曲状,主要来流风场并没有发生穿流形成明显的峡谷效应；风攻角范围分布在-9°和+7°之间,波动较大；湍流度与规范中D类地表规定值接近。2、利用数值模拟技术与逆向工程软件结合,建立了桥址处峡谷真实地形的大范围CFD模型生成方法,对桥址峡谷地形风场特性进行了CFD数值模拟。得到了完整模拟真实地形的技术路线以及比较合理的入口边界条件。研究表明单一的指数率风剖面并不满足峡谷地形风速随高度变化规律,风攻角分布超出设计考虑范围等结论,与实测结果形成对比。3、为了获得具有普遍意义的峡谷风场特性分布规律,建立了系列的简易峡谷数值模型,分析了风场分布规律与峡谷上下谷口宽度、坡度等参数的关系,并提出了拟合公式,可以作为此类地形桥址风参数确定的参考。本文主要通过现场实测和数值模拟两种研究方法,对澧水大桥桥位处山区峡谷风场特性进行研究。研究成果不仅对澧水大桥的正常运营起到指导作用,对后续此类山区风环境的研究工作也提供了参考。
[Abstract]:With the gradual implementation of the western strategy, more and more long-span flexible bridges will be built in the mountainous canyons of the central and western regions. In order to ensure the smooth construction and normal operation of such bridges, Accurate wind load input is a prerequisite for wind resistance design of long-span flexible bridges. However, the terrain of mountain canyon area is rugged and the environment is complex, so it is difficult to determine the parameters of wind field characteristics, and there is no detailed regulation on the wind field characteristics under the condition of canyon topography in the current bridge wind resistance code. Therefore, it is very necessary to study the wind field characteristics of mountain canyons. Based on the major project of the Ministry of Communications in the west of the Ministry of Communications, "Research on Monitoring and Simulation Technology of Wind and Rain effect of Super large Bridges", the characteristics of wind field at the location of Lishui Bridge are studied as follows: 1. A real-time monitoring system for the wind environment of the mountain canyon at the bridge site is established on the Lishui Bridge, and the characteristics of the canyon wind field at the bridge site are recorded truthfully and effectively. The average wind characteristics of canyon wind field, such as mean wind speed, wind direction, wind speed profile, wind attack angle, etc., as well as the fluctuating wind characteristics, such as turbulence degree, gust factor, turbulent power spectral density, etc., are obtained by analyzing the mean wind speed, wind direction, wind speed profile, wind attack angle and so on. The correlation of each characteristic parameter is fitted. The wind field at the bridge position of Lishui Bridge is affected by the terrain of mountain canyon, and its three-dimensional characteristics are remarkable. The results show that because the canyon of Lishui Bridge is curved, there is no obvious canyon effect in the main inflow wind field, and the wind attack angle is distributed between-9 掳and 7 掳, which fluctuates greatly. The turbulence degree is close to the specified value of Class D surface in the code. 2. Using the combination of numerical simulation technology and reverse engineering software, a large-scale CFD model generation method for the real terrain of the canyon at the bridge site is established. The CFD numerical simulation of the wind field characteristics of the canyon terrain at the bridge site is carried out. The technical route for simulating the real terrain and the reasonable entrance boundary conditions are obtained. The results show that the single exponential rate wind profile does not satisfy the conclusion that the wind speed varies with the height of the canyon terrain, and the distribution of wind attack angle exceeds the range considered in the design, which is compared with the measured results. 3, In order to obtain the characteristic distribution law of canyon wind field, a series of simple canyon numerical models are established, the relationship between the distribution law of wind field and the parameters such as the width and slope of the upper and lower valley mouth of the canyon is analyzed, and the fitting formula is put forward. It can be used as a reference for determining the wind parameters of this kind of topographic bridge site. In this paper, the wind field characteristics of mountain canyons at the bridge site of Lishui Bridge are studied by means of field measurement and numerical simulation. The research results not only play a guiding role in the normal operation of Lishui Bridge, but also provide a reference for the follow-up research work of this kind of mountain wind environment.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U442.59

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