跨线天桥表面列车风压主要影响参数研究

Main Influencing Parameters for Train-Induced Wind Pressure on Fly-Over Bridge

采用计算流体力学软件Fluent和滑移网格技术,结合k-ε二方程湍流模型,对高速列车通过跨线天桥时作用在天桥表面的列车风压进行数值模拟,研究跨线天桥的高度和宽度对其表面列车风压的影响。结果表明:跨线天桥宽度对天桥表面列车风压的影响很小,而高度的影响显著,天桥表面列车风压随跨线天桥高度的升高呈指数降低,且列车运行速度越高天桥表面列车风压下降的速度越快,天桥高度由5m升至10m条件下,车头和车尾经过时天桥迎风面的列车正风压极值分别下降78%和80%,负风压极值分别下降88%和85%,负风压极值比正风压极值的衰减速度更快;天桥底面的列车风压变化规律与迎风面类似;不同列车运行速度下天桥表面列车风压力系数的变化规律基本一致,即列车运行速度不影响天桥表面的列车风压力系数,据此建议用不同高度跨线天桥表面的列车风压力系数与其到列车中心线水平距离的关系曲线对现行高速铁路设计规范进行补充。

Combined with the two-equation k--ε turbulence model, CFD software Fluent and sliding mesh technology were adopted to simulate the train-induced wind pressure on fly-over bridge when high speed train passing and study the influence of bridge height and width on train-induced wind pressure. Results show that the width of fly-over bridge has little influence on train-induced wind bridge while the height has significant effect. The train-induced wind pressure on fly-over bridge decreases exponentially with the in- crease of bridge height. Moreover, the decline rate of wind pressure is faster along with the increase of train running speed. In addition, with the height of fly-over bridge increases from 5 m to 10 m, the posi- tive extreme values of windward train-induced wind pressure on fly-over bridge drop 78G and 80% in the cases of train head and tail passing bridge respectively, while the negative extreme values drop 88~ and 85 % respectively. It can be seen that the attenuation rate of the negative extreme value is faster than that of the positive one. The variations of train-induced wind pressure on the bottom and windward sides of fly- over bridge are similar. Under different train running speed, the coefficient variations of train-induced wind pressure on fly-over bridge are basically identical. That is, train running speed doesn＇t affect the coefficient of train-induced wind pressure. Hereby, it is recommended that the curve for the coefficient of train-induced wind pressure on fly-over bridge with different height and the horizontal distance to the cen- ter line of train should be supplemented into the existing code for the design of high speed railway.