流场能量牵引在铁路桥梁防风设计中的应用

南疆铁路至兰新高铁枢纽位于新疆著名的三十里风区,当地多次发生大风导致列车倾覆事件。本段桥梁是高铁与普铁联络线,针对高铁及普速铁路梁的特点综合分析,选用适宜梁型,结合挡风结构受力特点,运用流场数值计算、风洞试验、动力学仿真等方法展开研究,对梁体局部改造加强。通过分析强风场中列车受力特点,以及挡风屏结构高度等对风场影响的规律,在挡风屏设圆形及椭圆形交错开孔,通过紊乱气流自身损耗风能。人行道步板改用透风结构,减弱桥面顶板气流反冲力,改变列车附近的局部风场,降低横向风力对列车的冲击作用,对列车的安全运营提供了有力的保障。研究结论:(1)挡风结构制造紊流消耗有害风向,防护作用明显好于靠加强结构自身强度来抵抗风害;(2)对于气流进行疏导,对风场势能进行牵引,改变风荷载影响作用显著;(3)铁路桥梁结构防风设计,应该以风场势能的研究为主方向,局限于平面的受力关系研究势必会影响防风设计的思路。

Application of Flow Field Energy Traction in Windbreak Design of Railway Bridges

The South Xinjiang Railway to Lanzhou-Urumqi High Speed Railway Hub is located in the noted thirty-mile wind area of Xinjiang. The bridge serves as the connecting line between the high speed railway and the general speed railway. According to the comprehensive analysis of the beam characteristics of both the high speed railway and the general speed railway, the suitable beam type is selected and the wind retaining structure is combined based on stress characteristics. The numerical calculation of the flow field, the wind tunnel test and the dynamic simulation are carried out to study the local reconstruction of the beam body. By analyzing the stress characteristics of the train in strong wind field and the influence of the height of the wind barrier on the wind field, the circular and oval interlaced openings are set up in the wind barrier and the wind energy is consumed through the disturbance of the air flow itself. The crosswise structure is used to weaken the reverse impulse of the air flow on the roof of the bridge, change the local wind field near the train, reduce the impact of the lateral wind on the train, and guarantee effectively the safe operation of the train. The research finds that:(1) the wind structure generates turbulent flow to consume harmful wind, and its protective effect is obviously better than that of strengthening the structure's own strength to resist wind damage;(2) for the airflow to dredge, the wind field potential energy is traced, and the effect of changing wind load is significant.(3) the design of windproof for railway bridge structure should be based on the research of the potential energy of the wind field, and the research confined only to the force relation of the plane is bound to restrict the wind protection design.