竖井型长大城市隧道火灾通风的数值模拟

 随着城市建设发展，竖井型隧道越来越多地应用于城市交通隧道中。采用稳态与非稳态方法对火灾工况下竖井型隧道的气流场进行了数值模拟，分析了竖井型自然通风口对高温烟气扩散的影响。研究认为，竖井自然通风口引入隧道外冷空气，显著降低火源端部温度，可在一定程度上减少高温烟气对火源处隧道顶板的破坏。通过竖井引入新风，显著降低火源附近的有毒气体浓度，改善了火灾救援条件。火灾产生的有毒烟气由隧道洞口集中排放转变为竖井自然通风口分散排放，这对制定火灾救援、人员疏散方案有重要的指导作用。本隧道所设置的竖井自然通风口方案可满足火灾情况下人员逃生要求。

Numerical Simulation of Fire Ventilation in City Tunnels with Vertical Shafts

With the development of urban construction, tunnels with vertical shafts have been increasingly used in urban traffic tunnels. In this paper, steady and unsteady methods are used to simulate the airflow field of vertical-shaft type tunnels under fire conditions. The effect of vertical shaft natural ventilation opening on high temperature gas diffusion is analyzed. It is found that natural ventilation of vertical shafts introduces cold air outside the tunnel, significantly lowering the fire source temperature, to some degree reducing the damage of high temperature smoke and gases to the tunnel roof at the fire source. The introduction of fresh air also significantly lowers the concentration of toxic gases near the fire source, improving the rescue condition. The centralized discharge of toxic smoke and gases at the opening of tunnel terminal is changed to decentralized discharge at the natural ventilation opening of vertical shafts, which provides important guide for fire rescue and evacuation planning. The natural ventilation plan could meet the demand of fire escape.