摘 要 山区地形风场特性复杂，桥梁抗风已成为工程师备受关注的课题。关于内陆山区风效应研究资料甚少，现有的抗风规范也未对风场特性参数做出明确规定，有必要针对此类特殊地形风环境进行专门研究，为后期的风荷载和结构响应奠定基础。 特选取黄河喇叭口地形桥址区这一特殊位置，论述形成强风特性的原因，采用均匀流和B类风场两种来流开展地形风洞试验，分析对比此类地形条件下的平均风和脉动风特性参数的变化规律；运用ANSYS-FLUENT模块，选取Realizable k-ε湍流模型进行数值模拟，得到风环境绕流、风速场和湍流场分布情况；对比分析两种方法的研究结果，检验风洞试验和数值模拟的差异性，综合评判喇叭口地形桥址区强风特性风场分布规律；在收集桥址区附近气象站资料和相关学者的研究成果，总结并提出了4种计算基本风速的方法。 研究结果表明：喇叭口地形桥址区因风向角和测点位置不同，其平均风与脉动风特性发生了显著变化，计算结果值与现有规范差异较大；仅当风顺着河谷吹来时，风剖面符合传统模型，风速玫瑰图显示河谷中风速并未形成“加速效应”；湍流强度大多数符合随着高度增加而减小的规律；脉动风速功率谱在水平方向上，实测值与理论值相比在低频段偏低而高频段偏高，在竖直方向，谱频率随着高度增加有所减弱；风洞试验均匀流场风速值大于B类风场，但湍流强度值略小，相比之下B类风场的结果与规范值更为接近；最不利均匀流场下数值模拟计算的风速值和湍流强度值小于风洞试验值；经过最小二乘法拟合风速剖面指数，可归纳该桥址区地表类型为B类；偏安全考虑，本文提出的修正“抗风规范法”计算的基本风速值更为合理。

ABSTRACT The characteristics of wind field in mountainous terrain are complex，meanwhile the wind resistance of bridges has become a subject of great concern. There is very little information about wind effect in inland mountainous area，and the existing wind resistant code doesn’t specify the characteristics of wind field. It is necessary to study the wind environment of this kind of special terrain so as to lay the foundation for the later wind load and structural response. Selecting the special bridge site of the Yellow River that is trumpet topography and discussing reasons for the formation of strong wind characteristics. By using uniform flow and B wind field to carry out the wind tunnel test，then the variation laws of the mean wind and fluctuating wind characteristic parameters are analyzed and compared. With the ANSYS-FLUENT module，selecting Realizable k-ε turbulence model to simulate the flow field，wind velocity field and turbulent flow field. The results of the two methods are compared and analyzed. In the time，testing the difference of wind tunnel test and numerical simulation. It’s synthetically evaluated the wind field distribution law of strong wind characteristics in the area of trumpet topography. Based on the data collected from the meteorological station near bridge site and the research results of relevant scholars，Four methods to calculate the basic wind speed are summarized and put forward. The results show that due to the different wind direction and the location of measuring points，the mean wind and fluctuating wind characteristics have changed significantly. The calculated results are different from the existing codes. When the wind blows along the valley, the wind profile is consistent with the traditional model. Wind rose diagram shows that wind speed in the valley didn’t form an acceleration effect. Most of the turbulence intensity decreases with increasing height. In the horizontal direction，The fluctuating wind power spectrum where is the measured value is lower than the theoretical value in the low frequency range and higher in high frequency. In the vertical direction，the spectral frequency decreases with the increase of height. The velocity of uniform wind is greater than B wind field in wind tunnel test. But the turbulence intensity is slightly smaller. Compared with uniform wind，B wind field results is more closer to specification. Under the most unfavorable uniform flow field，the value of wind speed and turbulence intensity calculated by numerical simulation is less than wind tunnel test. After fitting the wind speed profile index by the least square method，it can be concluded that the surface area of the bridge site is B. Considering the partial safety，the basic wind speed calculated by the revised method of wind resistance is reasonable.