风沙流对戈壁风区桥梁防风栅响应规律的研究

Study on Response Law of Wind-blown Sand Flow Around Bridge Wind Fences in Gobi Wind Area

为明确兰新二线桥梁防风栅的防风效果以及防风栅背风侧流场分布情况,选取兰新二线新疆段桥梁中最具代表性的32 m箱梁结构建模,基于Fluent风沙两相流非定常模型,运用标准κ-ε湍流模型,对风沙环境下高速铁路桥梁及防风栅整体风场分布特征进行定性的模拟分析。结果表明:在设置单侧、双侧防风栅后,会在防风栅背风侧形成一个相对连续的风压减速区;在布置单侧、双侧风栅的情况下,防风栅背风侧距床面0.4 m高位置处风速变化规律基本呈现先减小再增大趋势,且不同高度条件下的风速垂直廓线基本一致,呈先增大后减小再增大的趋势,双侧防风栅背风侧的风速变化始终小于单侧防风栅;在双侧防风栅作用下,随着风速的增加,在距上行线道床面1.2 m以上至防风栅自身高度区间内风速变化保持稳定;防风栅在一定程度上会加剧桥梁轨道线路上方的积沙。

In order to clarify the windproof effect of the wind fences and the distribution of the leeward side flow field of the wind fences of the Lanxin Second Line bridge,the most representative 32 m box girder structure model in Xinjiang section of the Lanxin Second Line bridge was selected.Based on the Fluent wind-sand two-phase unsteady model and the standard κ-ε turbulence model,a qualitative simulation analysis of the overall wind field distribution characteristics of high-speed railway bridges and wind fences under wind and sand conditions was made.The results show that after setting one-sided and two-sided wind fences,a relatively continuous wind pressure deceleration zone will be formed on the leeward side of the wind fence;with the arrangement of one-sided and two-sided wind fences,the leeward side of the wind fence will be away from the bed surface,the change law of wind speed at the height of 0.4 m basically shows a trend of first decrease and then increase,and the vertical profile of wind speed at different heights is basically the same,showing a trend of first increase,then decrease and then increase.The wind speed change rule of the two-sided wind fences leeward side is always smaller than the one-sided wind fence;under the effect of the double-sided wind fences,as the wind speed increases,the wind speed change remains stable within 1.2 m from the bed surface of the upward lane to the height of the wind fence itself;to some extent,it will aggravate the sand accumulation above the bridge track.