Opencut tunnels are linear arch constructions that are being used as new structures to prevent sand encroachment on railway lines. The large size and shape of the contained structure affect the wind field around the structure in a manner different to how traditional constructions prevent sand accumulation. The present study identified the characteristics of wind velocity and flow fields in opencut tunnels in a wind-tunnel simulation. Results show that airflow having different wind angles (15°–90°) had different effects on the sand-accumulation-prevention characteristics of the opencut tunnel. The inflection point of a rapid change in wind speed was 6H (where H is the vertical height of the model) from the windward side of the opencut tunnel, and the position of an area of strong wind on the upper part of the opencut tunnel gradually moved to the windward side with an increase in the wind angle. This trend was not affected by a change in the indicated wind speed. The reattachment distance on the leeward side decreased with an increase in the wind angle, being 1H at 75°–90°, 2H at 30°–60° and 6H at 15° or less. The protection effect was best for a large angle of the main wind direction (exceeding 75°). Observed characteristics of the wind field show that the opencut tunnel is effective at all wind angles in preventing and controlling railway sand flow hazards and can thus ensure smooth railway operation.

明挖隧道是线性拱形结构，被用作防止铁路线路上的沙子侵蚀的新结构。所容纳结构的大尺寸和大形状以不同于传统建筑防止沙粒堆积的方式影响结构周围的风场。本研究通过风洞模拟确定了明挖隧道的风速和流场特征。结果表明，不同风向角（15°–90°）的气流对明挖隧道防沙积水特性的影响不同。从明挖隧道的上风侧开始，风速快速变化的拐点为6H（其中H为模型的垂直高度），随开挖角度的增加，明挖隧道上部强风区域的位置逐渐移向上风侧。该趋势不受指示风速变化的影响。下风侧的重新附着距离随着风角的增加而减小，在75°–90°时为1H，在30°–60°时为2H，在15°以下时为6H。对于较大的主风向角度（超过75°），保护效果最佳。观察到的风场特征表明，明挖隧道在所有风向下均能有效预防和控制铁路沙流危险，从而确保铁路畅通。下风侧的重新附着距离随着风角的增加而减小，在75°–90°时为1H，在30°–60°时为2H，在15°以下时为6H。对于较大的主风向角度（超过75°），保护效果最佳。观察到的风场特征表明，明挖隧道在所有风角下均能有效预防和控制铁路沙流危险，从而确保铁路畅通。下风侧的重新附着距离随着风角的增加而减小，在75°–90°时为1H，在30°–60°时为2H，在15°以下时为6H。对于较大的主风向角度（超过75°），保护效果最佳。观察到的风场特征表明，明挖隧道在所有风向下均能有效预防和控制铁路沙流危险，从而确保铁路畅通。