Taking the highway tunnel as the research object, the whole_size tunnel model was established. The critical wind velocity of longitudinal ventilation in highway tunnel fire under vehicular blockage was studied by FDS. Fire scales as 5, 10, 15, 20, 25, 30 MW and four types of vehicles upstream of the fire source were involved. The experimental simulation data were compared with those of the existing small scale tunnel fire test data. The results revealed that the critical ventilation velocity increases with the in-crease of fire scale under each blocking ratios, and the trend of vari-ation is basically the same. But for the same fire scale, the greater the blockage ratio of vehicles occupied, the greater the decreased proportion of the critical wind velocity. The reference value of the critical wind velocity of longitudinal ventilation in highway tunnel under the blocked conditions was given.%以公路隧道为研究对象,建立全尺寸隧道模型,通过FDS数值模拟方法对5、10、15、20、25、30 MW火灾规模及火灾上游4种车辆类型的阻塞下公路隧道火灾纵向通风临界风速进行研究,并将试验模拟得到数据与已有缩尺寸隧道火灾试验数据进行对比分析.结果表明:各阻塞情况下,临界风速的变化趋势基本一致,都随着火灾规模的增大而呈上升趋势;但同一火灾规模下,车辆占据阻塞比越大其临界风速减小比例就越大.给出阻塞情况下公路隧道纵向通风临界风速参考值.
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