开槽箱梁设置风障行车风环境模拟、试验与实测

Numerical and physical simulation and full-scale measurement of local wind environment around slotted box girder with wind barriers

摘要:

为合理评估桥面风环境以保障行车安全,首先采用CFD方法对设置风障时开槽箱梁桥面行车风环境进行模拟,然后对西堠门大桥主梁节段模型表面局部进行风环境测试,并开展了桥面局部风环境现场实测验证,进一步对桥面风障进行优化比选,分析设置风障条件开槽箱梁桥面风环境特点,采用CFD方法对设置不同风障型式的桥面局部风场进行模拟,分析不同车道位置处风速沿高度的变化规律,量化侧风折减系数随风障类型、高度和透风率的变化规律。结果表明:所采用的CFD数值模拟方法能够准确地模拟桥面风场特性并可再现桥面的局部风速演变趋势,分析误差在3%~9%之间,满足工程应用精度需求；设置风障对桥面风速分布的阻风改善效应显著,各车道风速折减率在30%~50%之间,风障的阻风有效区域与其横杆高宽比、高度、位置及透风率密切相关,其中风障透风率是决定风速折减效果的主要影响因素；除此之外,相较于整体式箱梁,由于开槽部位对来流具有的一定的分流作用,导致开槽断面下游主梁表面风速低于上游。

Abstract:

To reasonably assess the local wind environment around bridge decks, the CFD method was used to simulate the wind fields around a slotted box bridge with wind barriers. Experiments on the local wind environment of the model of Xihoumen Bridge girder were carried out, and field measurements of the bridge were conducted for verification. The wind barriers of the bridge deck were optimized and compared, and the wind environment characteristics of the slotted box girder with wind barriers were analyzed. The CFD method was adopted for simulating the local wind environment of the bridge deck installed with different types of wind barriers. The variation rules of wind speed at different positions of lanes along different heights were analyzed, and the influences of types, heights, and porosities of wind barriers on the crosswind reduction factor were quantified. Results show that the CFD method could provide highly accurate results and reveal more detailed characteristics of actual flow-fields around the bridge deck. The deviation was between 3% and 9%, which met the accuracy requirement of engineering application. Wind barriers had significant effects on reducing the wind speed under the condition of crosswind, and wind speed reduction on different lanes was about 30%–50%. The effective wind reduction regions of wind barriers were closely related to the height-width ratios, heights, positions, and porosities of the barriers, among which porosity was the crucial factor that decided the crosswind reduction effects of wind barriers. In addition, compared with integrated box girder, the wind speed on the downstream surface of the slotted box girder was obviously lower than that on the upstream surface due to the dredging effects of the center slot.