内外出口宽度对避难通道疏散能力的影响

摘要

In this paper,evacuation capacity of fire-protection with different width of intemal and external opening in an underground large space building was investigated.A fire district with the area of 2 000 m2 was set according to the item of the code in the paper,and the number of occupants was determined by the occupant density in underground commercial areas.Fire-protection evacuation walks were set along the two sides or in the middle of the fire district.BuildingEXODUS was used as the simulation tool to calculate evacuation time of occupants in the district.Fire-protection evacuation walks set along the two sides of the district have higher evacuation capacity than they are set in the middle of the district when their entrance width are almost the same.The number of entrance and its width has great effects on evacuation time.The evacuation time became steady when the width ratio of internal and external opening is greater than 0.8.In such situation,the evacuation time was determined by evacuation capacity of the fire-protection evacuation walk.The results show that increase the width of the entrance of the fire-protection evacuation walk can reduce the evacuation time if there is no congestion in the walk.Under this circumstance,we can design a wider entrance for a walk while not be restricted by the item of current codes which says" in a fire district with the largest number of occupants,the net width of a fire-protection evacuation walk should not less than all exits width leading to the walk".We can reduce evacuation time effectively and make occupants more safely by designing the width,the number and the distribution of the entrance optimally.%目的 研究地下大空间建筑中不同内外出口宽度的疏散通道的疏散能力.方法 根据规范设置一个2000 m2的独立防火分区,并根据地下商场人员密度获得防火分区内的人数.在防火分区的两侧及中心分别布置不同宽度的避难通道,利用BuildingEXDOUS软件作为仿真工具模拟人员疏散时间.结果 在通道入口宽度基本一样的情况下,靠防火分区两侧布置的疏散通道比中心布置的疏散通道具有更大的疏散能力.避难通道入口个数和宽度对疏散时间影响很大,当内外出口的宽度比大于0.8以后,人员的疏散时间将趋于稳定,此时疏散时间受疏散通道疏散能力的限制.在走道内不发生拥堵时应适当加大避难通道入口的宽度以减少疏散时间.结论 在走道内不发生拥堵的情况下,应适当加大避难通道入口的宽度,甚至可以突破现行规范规定的“避难走道的净宽不应小于设计容纳人数最多的一个防火分区通向避难走道各安全出口最小净宽之和”这一要求.对避难通道入口的宽度、开口个数和布置位置进行优化设计可有效减少疏散时间,保证人员的安全疏散.