基于现场实测与数值模拟的深切峡谷风场特性精细化研究

Strong wind characteristics of the deep gorge area not only relating wind resistant design code, but also wind properties great differently comparing with the sea crossing, cross river, plain open area, such as the wind speed and turbulence characteristics and spatial correlation characteristics. Fine study on the distribution law of the deep gorge wind characteristics based on wind field measurement, and extendedly researched by numerical simulation in the project. The main contents include as follows. The wind field measurement systems of the deep gorge characteristics are optimized and designed. The wind parameters of the gorge wind and the flow over mountains are extracted. The three-dimensional spatial distribution of the wind field characteristics of 3D gentle hills, complex terrain and deep gorge are simulated based on Large Eddy Simulation. The distribution characteristics of the wind profiles, wind direction and wind attack along different height and regions are analyzed. The spatial correlation and the two-dimensional wind profiles models are established along vertical the deep gorge. The turbulence intensity, turbulence integral scale, fluctuating wind power spectrum and spatial correlation feature of the turbulence wind are researched along different height and regions. The accelerating effect, wind profiles, and turbulence characteristics of the wake region of the flow over mountains are studied. Above researches, the models of the mean wind, turbulence wind and spatial correlation of the deep gorge are established. The distribution laws of the deep gorge are revealed between the wind field characteristics and complex terrains. The feasibility of the numerical simulation technology of the deep gorge wind features is validated. The wind field measurement and numerical simulation technologies are developed in the wind engineering. It can be providing the reference and basis for the large bridge design and construction in China's mountains area.

深切峡谷的强风特性不仅没有抗风设计规范，而且与跨海、跨江、平原空旷区的风特性相比，风速设计特性、湍流特性和空间相关性差别都极大。本项目以风场实测数据为基础，数值模拟为扩展研究方法，针对深切峡谷风场特性的分布规律精细化研究。主要内容包括：风场特性实测系统的优化设计；峡谷风和越山风的风速风向参数提取；基于大涡模拟的三维平缓山丘、复杂地形、深切峡谷风场特性的三维空间分布数值模拟；不同高度区域的风剖面、风向角和风攻角分布特性；垂直于峡谷走向的二维风剖面及空间相关性模型；不同区域的湍流强度、湍流积分尺度、脉动风功率谱及空间相关性模型；越山风的加速效应、风剖面及尾流区域的湍流特性。通过上述研究，建立深切峡谷的平均风、湍流风及空间相关性模型；揭示深切峡谷风场特性与复杂地形之间的分布规律，验证深切峡谷数值模拟技术的可行性，发展风工程的风场实测和数值模拟技术，为我国峡谷区大跨桥梁的设计与施工提供参考依据。

深切峡谷风场特性具有风速空间分布不均匀、风攻角大及紊流度高等特点，对大跨度悬索桥的气动稳定性产生较大影响。本项目选取矮寨大桥桥址深切峡谷区为典型背景工程，购置安装了10个风速传感器的实测系统，结合CFD数值模拟方法，开展了深切峡谷风场特性分布规律的精细化研究。主要内容包括：实测系统的优化布置、实测数据挖掘技术与数据处理程序的编制、风场特性的统计与数学模型分析，以及CFD数值模拟结果与实测数据的对比验证与研究。综合典型背景工程的现场实测与数值模拟结果，得到峡谷风场特性重要结论如下：.（1）沿峡谷走向风剖面指数服从幂指数分析，地表粗糙度系数拟合值为0.193，介于B类与C类风场之间；.（2）强风记录风向玫瑰图表明，峡谷风向与峡谷走向基本一致；风向不同，风攻角明显不同，风攻角大致介于-3.5°和+5°之间，高于平原地区的-3°和+3°；.（3）峡谷风三向的湍流强度介于0.1-0.3之间，湍流强度概率密度与湍流度的分布符合正态分布，湍流强度与10分钟平均风速符合指数函数分布；.（4）Kaimal数学模型能够很好地拟合峡谷风湍流功率谱密度函数；.（5）峡谷风风向不同，沿桥轴线的风速分布明显不同，偏北风时，茶洞岸风速略高于跨中和吉首岸；偏南风时，跨中风速明显大于两侧。.本项目针对深切峡谷风场特性的复杂性，开展了现场实测与CFD数值模拟的精细化研究，分析了峡谷风场参数与复杂地形之间的分布规律，得出了部分风参数的统计规律与数学模型，完成了项目计划的全部内容。获发明专利3项，已公开发表论文5篇。