一端封闭隧道施工中火灾烟气流动的数值模拟分析

Analysis on numerical simulation to fire smoke flow in being constructed tunnel with one closed-end

火灾条件下影响安全疏散的因素包括隧道中烟气流动性及其温度随时空的分布。针对一端封闭的隧道火灾情形,采用临界温度与临界视距判据,对一端封闭的长300 m掘进中的隧道进行了数值模拟,获得了温度与烟气浓度分布随时空的变化规律,发现其温升速率沿隧道纵向按指数规律衰减,而且临界温度与临界视距交错出现。

In this paper, we have proposed a numerical simulation method for the fire smoking torrent in a tunnel with its one end dead under construction about 300 m long. The purpose of the simulation is to emulate the way of evacuation in case of a tunnel fire in accordance with the criteria of the critical temperature and critical visibility. The real problem here is to find the regularity of temperature distribution and smoke density or the extinction coefficient in regard to the space and time as the reference parameters. The factors to be chosen for safety evacuation mainly include the smoke behavior and the tempera- ture distribution in term of space and time in the tunnel in case of get- ting fire. That is to say, the temperature rising rate （TRR） would de- cay exponentially along with the longitudinal direction of the tunnel whereas the critical temperature and critical visibility inside is chang- ing alternatively, that is to say, at the location of about 120 m from the closed-end in the tunnel fire, the critical temperature is prior to critical visibility but, beyond the location, critical visibility is prior to critical temperature. So the Available Safety Egress Time （ASET） mainly relates with the critical temperature and the critical visibility in the tunnel fire, that is to say, beyond the location of about 120 m, the required time for the critical temperature should be taken into account whereas the required time for the critical visibility accounts beyond the location. These results arc of key significance for the practical personnel evacuation in the on-fire tunnel.