侧壁排烟模式下超宽断面沉管隧道火灾排烟效率研究

排烟效率是衡量火灾期间隧道排烟效果的重要指标。为得到侧壁排烟模式下超宽断面沉管隧道排烟特性,通过数值模拟计算对依托工程进行研究,分析排烟孔间距、排烟孔面积、排烟孔布置形式、沉管隧道宽度等因素对排烟效率的影响。结果表明:增加排烟孔数量可提高排烟效率;当排烟孔按三个一组布置时,增大排烟组间的间距有利于排烟;排烟孔均匀布置的排烟效率高于按三个一组布置;排烟孔开启数量相同时,增大排烟孔开口面积可提高排烟效率;随着沉管隧道宽度的增加,排烟效率降低,单向两车道情况下排烟效率为93.7%,单向四车道情况下排烟效率仅为45.94%。对于单向四车道超宽沉管隧道,侧壁排烟方式适用性较差。

Study on the Efficiency of Smoke Exhausting under Lateral Exhaust Mode in Extra-Wide Immersed Tunnel Fire

Smoke exhausting efficiency is an important indicator in the smoke exhausting effectiveness measurement of tunnel during fire.In order to obtain the smoke exhausting characteristics of extra-wide cross section immersed tunnel,numerical simulation was carried out to analyze the influence of different factors on smoke exhausting efficiency,including the distance,area and layout of exhausting valves and the width of immersed tunnels.The results are as follows:the increase of exhausting valves can facilitate smoke exhausting efficiency.When exhausting valves are arranged in groups and each group consists of three valves,the increase of distance between groups is helpful for exhausting smoke.The smoke exhausting efficiency of evenly arranged valves is higher than that of valves divided into three-valve groups.When the number of exhaust valves is equal,increasing the area of valves can improve the efficiency of smoke exhausting system.The width increasement of immersed tunnel results in the decrease of smoke exhausting efficiency.The smoke exhausting efficiency of two-lane,uni-directional tunnel is 93.7％;While that of four-lane,uni-directional ones is only 45.94％.The lateral exhaust mode is not suitable for fourlane,uni-directional extra-wide immersed tunnel.