盾构铁路隧道坡度对火灾烟气蔓延的影响研究*

为研究坡度隧道内列车阻滞后的火灾烟气蔓延行为，利用火灾动力学模拟软件（FDS）建立盾构铁路隧道火灾模型和CRH6高速列车阻滞模型，隧道坡度分别为0%、1.0%、1.5%、2.0%、2.5%、3.0%、3.5%和4.0%，通过分析隧道内烟气、温度、能见度等特征参数的变化规律，研究坡度隧道内高温烟气的受力情况，探讨坡度变化对火灾烟气蔓延的作用机理。结果表明，坡度隧道内发生火灾，随着烟气的蔓延，隧道内形成沿坡度方向的烟囱效应力，使得烟气在火源两侧呈不对称分布。火源下游区域的高温烟气在火风压和烟囱效应的协同作用下蔓延速度比上游更快，下游烟气层分界中性面与隧道轴线平行，上游烟气层分界中性面呈现水平状态。有坡度的铁路隧道内发生火灾，建议向火源下游方向施加纵向机械通风，人员向火源的上游方向疏散逃生更安全。

Study on influence of slope on fire smoke spread in shield railway tunnel

In order to study the fire smoke spread behavior after the train blocks in the slope tunnel,a fire model of shield railway tunnel and a block model of CRH6 high-speed train were established by using the Fire Dynamics Simulation (FDS) software.The tunnel slopes were set to be 0%,1.0%,1.5%,2.0%,2.5%,3.0%,3.5% and 4.0%,respectively,through analyzing the change laws of characteristic parameters such as smoke,temperature and visibility in the tunnel,the force status of high-temperature smoke in the slope tunnel was studied,and the action mechanism of slope change on the fire smoke spread was discussed.The results showed that when the fire occurred in the slope tunnel,with the spread of smoke,the stack effect force along the slope direction was formed in the tunnel,which made the smoke distribute asymmetrically on two sides of fire source.The high-temperature smoke in downstream region of fire source spread faster than that in upstream region under the synergistic effect of fire wind pressure and stack effect.The neutral surface of the smoke layer in downstream region was parallel to the tunnel axis,and the neutral surface of the smoke layer in upstream region presented a horizontal state.In case of a fire in slope railway tunnel,it was recommended to apply longitudinal mechanical ventilation to the downstream direction of fire source,and it was safer for people to evacuate to the upstream direction of fire source.