防排烟系统对拱形地铁站厅烟气蔓延的影响

地铁站厅防排烟系统对人员安全疏散具有致关重要的作用。通过烟气层沉降理论分析,编写了适用于拱形地铁站厅火灾烟气蔓延区域模型程序,研究不同机械排烟量下烟气沉降高度随时间的变化规律。研究表明,随着排烟量的增加,烟气层沉降速度变慢,排烟量为28.4 m³/s时,360 s左右烟气层方才达到溢出口高度,该设计排烟量能满足人员安全疏散要求。通过火灾动力学软件FDS数值模拟的方法,研究不同排烟量和挡烟垂壁高度对地铁站厅能见度、CO浓度的影响。研究表明,烟气从高大站厅空间向狭小的通道空间溢出,容易在通道出口处形成烟气堆积,导致通道出口处能见度最低,CO浓度最高;验证了烟气层沉降理论计算地铁站厅烟气排烟量可以满足人员安全疏散的要求;设置挡烟垂壁可以提高地铁站厅的能见度和降低其CO浓度。

Influence of Smoke Control and Exhaust System on Smoke Spread in the Hall of Arch Subway Station

The smoke control system of subway station hall plays an important role in the safe evacuation of people. Based on the theoretical analysis of smoke layer settlement, a model program suitable for the fire smoke spread area of arched subway station hall is compiled to study the variation law of smoke settlement height with time under different mechanical smoke discharge. The study shows that with the increase of smoke exhaust volume, the settling velocity of the smoke layer becomes slower. When the smoke exhaust volume is 28.4 m³/s, the time of smoke layer reaches the height of the overflow outlet is about 360 s. The designed smoke exhaust volume can meet the requirements of safe evacuation of personnel based on the theoretical analysis. Through the numerical simulation method of Fire Dynamics Simulator (FDS), the influence of different smoke exhaust volume and smoke barrier wall height on the visibility and CO concentration of subway station hall is study.The research shows that the smoke spills from the tall station hall space to the narrow passage space, which tends to form the accumulation of smoke at the exit of the passage, resulting in the lowest visibility and the highest CO concentration at the exit of the passage. The numerical simulation method is verified that the smoke exhaust volume calculated by the theory of smoke deposition can meet the requirement of safe evacuation. The smoke-blocking wall can improve the visibility and reduce the CO concentration of the subway station hall.