区间坡度对停驶地铁列车火灾烟气自然扩散的影响

Influence of slope on the fire smoke spread of trains staying in the subway tunnel

采用三维场模拟与一维网络模拟相耦合的多尺度模拟方法,对列车中部着火且相邻车站风机未启动阶段的烟气自然扩散进行研究。地铁长区间隧道坡度分别为0‰、12‰、21‰、30‰,分析坡度对区间隧道火灾烟气扩散及控制产生的影响。综合分析温度、CO浓度和能见度等因素,研究了火灾初期隧道环境随时间变化的危险性,确定了人员可利用的安全疏散时间。列车阻塞于区间隧道的坡度区段时,当坡度达到30‰,由于回流现象的出现导致隧道内CO浓度出现了阶跃性变化。

A multi-scale simulation method coupled with threedimensional field simulation and one-dimensional network simulation was used to study the natural propagation of smoke when the train is on fire at the middle and the fans in adjacent stations are closed.The slopes of the long subway interval tunnels are 0‰,12‰,21‰and 30‰.The influence of slope on smoke diffusion and control in tunnel fire was analyzed.Comprehensive analysis on factors such as temperature,CO concentration and visibility was carried out,the danger of tunnel environment changes over time in the initial stage of the fire was studied and the available safe evacuation time for personnel was obtained.When the train is blocked in the gradient section of the section tunnel and the gradient reaches 30‰,there is a step change of CO concentration in the tunnel because of the backflow phenomenon.