运用FDS对不同烟囱高度的竖井型隧道着火时烟气扩散情况进行模拟,得到隧道内温度和CO体积分数的变化特征及烟气纵向蔓延规律和沉降规律.结果表明,竖井型隧道采用自然通风能起到很好的排烟效果.火源正上方产生的高温对隧道顶棚结构具有较大的威胁,但火源附近安全高度处烟气温度迅速降到环境温度,不会对人员安全疏散构成威胁.安全高度处CO体积分数随时间的增加呈上升趋势,且随着与火源距离的增加先增加再降低至0.在300 s内各处烟气均没有降到安全高度1.75m以下,对人员疏散影响较小,人员有足够时间疏散至敞开段.%The smoke diffusion at different chimney heights in a tunnel with vertical well was simulated by FDS.We can get the changes of temperature and CO concentration,and the discipline of vertical diffusion and sedimentation of smoke.The results show that it is feasible and good to use natural ventilation as a smoke extraction mode in tunnels with vertical well.The high temperature above the ignition sources poses a great threat to the tunnel roof structure.However,the smoke would not pose a threat to the evacuation if the smoke temperature at the safe height around ignition sources can drop to the ambient temperature rapidly.Along with the increase of time,the CO concentration at the safe height increases.And with the increase of the distance of ignition sources,the CO concentration increases first and then decreases to zero.The smoke can not reach the height of 1.75 m in 300 seconds,which has less affection to the evacuation and ensure adequate time to flee to the open area.
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