特长公路隧道火灾烟气沉降特性对人员疏散影响的研究*

为研究特长公路隧道火灾烟气沉降对人员疏散安全的影响，通过数值模拟方法，对0，1.0，1.5 m/s和临界风速值4种不同纵向通风风速下隧道火灾烟气沉降特征进行研究，并分析不同风速下烟气沉降对人员疏散的影响。研究结果表明:在无纵向风时，烟气沉降现象较为明显，烟气下沉造成的不均匀烟气温度、能见度分布，提前终止人员疏散的进行；随着纵向风速的增加，沉降现象仍存在，但沉降点后移，对人员疏散的影响减小；在1.5 m/s的纵向通风条件下，火源下游500 m范围内烟气基本不发生沉降且能维持分层，此时几乎不影响火灾下游人员疏散。在实际应用中，火灾初期可先以1.5 m/s的分层风速值进行通风，待下游人员疏散后，再施加临界风速加快烟气排出。研究结果可为特长公路隧道火灾防治和疏散救援提供参考。

Research on influence of fire smoke descent characteristics on personnel evacuation in extra-long highway tunnel

In order to study the influence of fire smoke descent on safety of personnel evacuation in the extra-long highway tunnels,the smoke descent characteristics of tunnel fire under four different longitudinal ventilation wind velocities of 0 m/s,1 m/s,1.5 m/s,and critical wind velocity were studied by numerical simulation,and the influence of smoke descent on personnel evacuation under different wind velocities was analyzed.The results showed that the smoke descent phenomenon was more obvious without longitudinal wind.The smoke descent caused the uneven distribution of smoke temperature,and visibility,which terminated the personnel evacuation early.As the longitudinal wind velocity increased,the descent phenomenon still existed,but the smoke descent position was backward,and the influence on personnel evacuation was reduced.Under the longitudinal ventilation condition of 1.5 m/s,the smoke did not descend basically and maintained stratification within 500 m downstream of the fire source,and the smoke descent did not affect the personnel evacuation downstream of the fire at this time.In practical application,the ventilation with the stratified wind velocity of 1.5 m/s could be carried out at the beginning of fire,and after the evacuation of personnel downstream,the critical wind velocity could be applied to speed up the smoke exhaust.The results can provide reference for fire prevention and evacuation of extra-long highway tunnels.