Zhang Xian, Xie Shengbo, Pang Yingjun
Research Laboratory of Desert and Desertification / Dunhuang Gobi and Desert Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Heliyon. 2024 Dec 26;11(1):e41515. doi: 10.1016/j.heliyon.2024.e41515. eCollection 2025 Jan 15.
Railway bridges with lower beam bottom clearances in windblown sand areas tend to accumulate sand particles on the sides of the beams, which seriously impacts railway safety. To investigate the effect of beam clearance height on wind-sand movement near the surface, and to determine the minimum clearance height for railway bridges in such areas, computational fluid dynamics using the Euler-Euler two-phase flow model was employed to simulate the wind-sand flow field beneath bridges with different heights. The results indicated that as clearance height increased, both the high-speed area above the bridge and acceleration area under the bridge increased, while the turbulence area on the leeward side remained unchanged. Furthermore, wind speed on the windward side did not decrease, and no deceleration zone near the surface was observed with increased clearance height. When the bridge height reached 9 m, the wind speed on the windward side no longer decreased. The correlation coefficients of near-surface wind speed under the bridge height of 9 m and above were consistent. As wind speed increased, the fluctuations in wind speed between bridges with different clearance heights became more pronounced, with differing variation trends. On the leeward side, lower clearance heights resulted in greater wind speed fluctuation. With higher wind speeds, the main position of wind speed deceleration moved further from the bridge. Therefore, the clearance height of bridges in the windblown area should be at least 9 m. These results provide a theoretical basis for the survey and design of bridges in the windblown sand areas.
风沙地区梁底净空较低的铁路桥梁，梁侧易积沙，严重影响铁路安全。为研究梁净空高度对近地表风沙运动的影响，确定该地区铁路桥梁的最小净空高度，采用基于欧拉 - 欧拉两相流模型的计算流体力学方法，对不同高度桥梁下方的风沙流场进行模拟。结果表明，随着净空高度增加，桥梁上方高速区和桥下加速区均增大，而背风侧紊流区不变。此外，迎风侧风速未减小，且随着净空高度增加未观察到近地表减速区。当桥梁高度达到9米时，迎风侧风速不再减小。9米及以上桥高桥下近地表风速的相关系数一致。随着风速增加，不同净空高度桥梁间风速波动更明显，且变化趋势不同。在背风侧，净空高度较低导致风速波动更大。风速越高，风速减速主要位置离桥梁越远。因此，风沙地区桥梁净空高度应至少为9米。这些结果为风沙地区桥梁勘察设计提供了理论依据。
