分岔隧道排烟策略下火灾烟气输运特性研究
Study on characteristics of fire smoke transportation under smoke exhaust strategy of bifurcated tunnels
摘要：
以某分岔隧道为例,对发生火灾时不同通风方案下隧道内的温度场及烟气的蔓延规律进行了模拟研究,分析了匝道风压、主隧道出口段风压、主隧道加宽段风压对火灾烟气输运特性的影响。工况1与工况2分别采用提高匝道风压与提高主隧道出口段风压的通风方案,对比2种工况下温度场变化得知主隧道出口段通风效果优于匝道。工况3采用提高主隧道加宽段风压的通风方案,随着主隧道加宽段风压的增大,主隧道内高于60 ℃的高温区域不断缩小,主隧道出口段与匝道2 m高度内温度逐渐降低,主隧道加宽段风压的增大对隧道排烟有利,但并不显著。工况4采用增大匝道风压的通风方案,主隧道2 m高度内温度降低,匝道2 m高度内温度升高,增大匝道风压,匝道的排烟效果明显,由于匝道断面小,可考虑作为排烟通道。
Abstract：
Taking a bifurcated tunnel as an example,a simulation study is carried out on the temperature field and smoke spread law in the tunnel under different ventilation schemes during a fire,and the impacts of the wind pressure in the ramp,the wind pressure in the exit section of the main tunnel,and the wind pressure in the widened section of the main tunnel on the smoke transportation characteristics of the fire are analysed.The ventilation scheme of increasing the wind pressure in the ramp and the exit section of the main tunnel is adopted in condition 1 and condition 2,respectively.Comparing the temperature field changes under the two conditions,it is found that the ventilation effect in the exit section of the main tunnel is better than that in the ramp.Condition 3 adopts a ventilation scheme to increase the wind pressure in the widened section of the main tunnel.As the wind pressure in the widened section of the main tunnel increases,the high temperature area above 60 ℃ in the main tunnel continues to shrink,and the temperature within the height of 2 m in the exit section of the main tunnel and the ramp gradually decreases.The increase of the wind pressure in the widened section of the main tunnel is beneficial to tunnel smoke exhaust,but it is not significant.Condition 4 adopts the ventilation scheme of increasing the wind pressure in the ramp.The temperature within the height of 2 m in the main tunnel decreases,and the temperature within the height of 2 m in the ramp increases.If the wind pressure in the ramp is increased,the smoke exhaust effect of the ramp is obvious.Due to the small cross-section of the ramp,it can be considered as a smoke exhaust channel.
Keywords:bifurcated tunnel; fire; smoke exhaust; smoke transportation; ventilation; wind pressure; main tunnel; ramp