楼梯结构对烟气蔓延及安全疏散的影响研究

Research on the influence of staircase structure on smoke spread and safe evacuation

为研究高层建筑火灾中楼梯结构对烟气蔓延的影响,运用PyroSim软件建立不同结构楼梯间的数值模型,使用FDS软件进行火灾烟气蔓延数值模拟,观测记录不同工况下烟气宏观高度随时间的变化,通过SPSS软件对观测值进行拟合分析,再结合烟气蔓延过程中楼梯间的温度、能见度及CO体积分数的变化情况,对人员安全疏散条件进行分析。结果表明:不同楼梯结构对烟气蔓延的阻碍作用差异明显,并且烟气在不同结构楼梯间内蔓延的宏观高度与时间均呈二次函数关系,其中具有中部隔墙结构的楼梯间防烟效果最佳,无梯井结构的楼梯间次之,存在梯井结构的楼梯间防烟效果最差,但综合各因素考虑,无梯井结构的楼梯间更有利于人员安全疏散。

To study the influence of staircase structure on smoke spread in a high-rise building fire,we used PyroSim software to establish numerical models of the staircase with different structures,and utilized FDS software to simulate the spread of fire smoke.The changes of the macroscopic height of smoke with time under different working conditions were observed and recorded,and the observation results were fitted and analyzed by SPSS software.Besides,measurement points or monitoring cuts for temperature,visibility,and CO volume fraction were set up at different locations in the stairwell to analyze the variation of each parameter over time.Finally,combined with the simulation results,the safety evacuation conditions of all working conditions are analyzed.The results show:Firstly,the macroscopic height of the flue gas spreading in all structural stairwells has a quadratic function relationship with time,but the obstruction effect of different stair structures on smoke spread is obviously different.The smoke prevention effect of the staircase with stairwell structure is the worst,and it takes 430 s for smoke to spread from one floor to eighteen floors.The staircase without the stair-well structure takes 740 s,and the staircase with mid-partition structure has the best smoke protection and requires 825 s.Secondly,staircase structure also has a significant influence on local temperature and CO volume fraction,the maximum temperature at 1.5 m on the first floor of the staircase with mid-partition is about 105℃,while the maximum temperature at the same position of the staircase with stair-well is 86℃and the staircase without stair-well is only 78℃.In addition,the CO volume fraction at 1.5 m in the staircase with mid-partition is about 47%higher than the former.Taking into account the various factors affecting the safe evacuation of people,the staircase without stair-well is more conducive to personal escape.The innovative point of this paper lies in using the function fitting method for quantitative analysis and predicting the stairs’smoke spreading for the first time,providing theoretical and methodological guidance for performance-based smoke prevention design of buildings.