铁道建筑

针对外覆式半封闭声屏障在不同时速、多车交会工况下，车致脉动风荷载空间分布规律不明、规范缺少设计参数、结构抗风揭性能偏弱等问题，本文以西成高铁东平车站单、三线桥外覆式声屏障为研究对象，采用重叠网格法，揭示列车通过声屏障内壁风压变化规律，量化车速与行车工况对荷载幅值的影响，明确最不利工况及结构薄弱部位，为该类结构的设计与施工提供理论支撑。结果表明：列车通过时声屏障内壁风压由压缩波与膨胀波主导，呈典型升降回升规律；脉动风压幅值与车速呈近似平方关系增长，拟合指数2.09～2.24，车速每提升100km/h荷载增大约2.1倍。三线桥交会工况荷载显著高于单线，三车对开2、对开3分别为最不利负压、正压工况。风压竖向呈底部大、中部次之、顶部小分布，纵向呈跨中大、端部小分布，三线桥受力不均程度更高。

This study targeted the unresolved problems of external-clad semi-enclosed noise barriers on high-speed railways: unclear spatial distribution of train-induced fluctuating wind loads under variable speeds and multi-train crossing conditions， a lack of specified design parameters in current codes， and relatively insufficient wind uplift resistance. Taking single-track and three-track external-clad noise barriers at Dongping Station of Xicheng High-speed Railway as objects， numerical simulation was conducted using the overset grid method to reveal dynamic pressure characteristics on the inner wall during train passage， quantify the effects of speed and operation conditions on load amplitudes， and identify the most unfavorable cases and vulnerable regions， providing theoretical support for the design and engineering application of such barriers.Research conclusions：(1) The aerodynamic pressure on the inner wall is governed by compression and expansion waves， showing a distinct rise-peak-drop-rebound pattern.(2) The fluctuating wind pressure increases approximately with the square of train speed， with a fitting exponent ranging from 2.09 to 2.24; the load amplitude rises by about 2.1 times per 100 km/h increment in speed.(3) Loads under crossing conditions on three-track bridges are significantly higher than those on single-track bridges. Three-train meeting 2 and three-train meeting 3 represent the most unfavorable negative and positive pressure cases， respectively.(4) Vertically， wind pressure is large at the bottom， moderate in the middle， and small at the top. Longitudinally， pressure is greater in the mid-span and smaller at the ends. Load non-uniformity is more significant on three-track bridges.