隧道及其上方城市环境污染物传播规律数值模拟研究

Numerical Simulation of Urban Environmental Pollutant Propagation in Tunnel and Above

构建了一个含地上建筑环境、地下S形城市隧道、地上丁字形机动车道等几何结构的三维城市模型,运用计算流体力学模拟方式,首先数值分析了整体计算域流场及污染物分布特性,进而探究了环境风向及风速等影响因素。结果表明:开口贯通处对缓解下方S形隧道内污染作用明显,经南开口贯通处后污染降低约60%,但上方建筑环境则因此污染加重,西南区受影响较为突出,且在北偏东NbE=60°时将受到最大程度的渗透及污染影响,约为最低值NbE=30°时的3.5倍;随风速增加建筑环境整体污染呈下降趋势,但风速增至2.5 m/s及以上时,污染降幅有所减小,风速敏感性减弱,且西南区建筑环境南半段较北半段受风速影响的敏感性更高。

A three-dimensional urban model with geometric structure is constructed,such as above-ground built environment,underground S-shaped urban tunnel and above-ground T-shaped motorway.Based on computational fluid dynamics simulation method,firstly,the flow field and pollutant distribution characteristics of the whole calculation domain are numerically analyzed,and then the influencing factors such as wind direction and wind speed are explored.The results show that the opening has a significant effect on mitigating the pollution in the S-shaped tunnel below,and the pollution decreases by about 60%after passing through the south opening.However,the surrounding built environment above the opening is more polluted and the buildings in the southwest district are affected more significantly.In the case of NbE=60°,the built environment in the southwest region will be affected by the maximum degree of infiltration and pollution,and the degree of infiltration is about 3.5 times that of the lowest NbE=30°.With the increase of wind speed,the overall pollution of built environment shows a downward trend.However,when the wind speed increases to 2.5 m/s or above,the pollution reduction amplitude and sensitivity will be decreased.In addition,the southern half of the southwest architectural complex is more sensitive to wind speed than that of the northern half.