Based on the similarity theory, a metro transfer station with screened gate station on platform in Beijing was used as an example to build a model test bench with geometric scale of 1∶20 and a temperature difference scale of 1∶6. High temperature radiation flow induced by a strong heat source was used to substitute fire source.The temperature distribution of B3 platform and the distribution of stairway velocity under three different smoke extraction schemes were investigated when a 2 MW fire occurred at the platform of B3 (corresponding to the underground three floors of the physical station) of the metro transfer station.The result showed that the smoke temperature on the ceiling will decay when smoke spreads along the length of the platform, and a large temperature drop occurs at the position of the stairs.At the height of the human eyes, the temperature decreases with the distance from the center of the fire increases, and at the stairway location, the temperature rises due to the deposition of smoke. The maximum wind speed down the stairs is 1.4 m/s under the condition of opening the B3 screen door, the B3 platform exhaust system, the B3 rail exhaust system and the B2 platform air supply system when the fire broke out. At this time, the amount of exhaust smoke should be increased and the tunnel exhaust system must be opened.%基于相似理论,以北京某站台带有屏蔽门的地铁站为例搭建几何比尺为1∶20、温差比尺1∶6的模型实验台,以强热源诱导的高温辐射流代替火源,研究地铁换乘站在B3层(对应实体车站的地下三层)站台发生2 MW的火灾时,3种排烟方案下B3站台层温度及楼梯口速度分布.结果表明:烟气温度在顶棚高度沿站台长度方向蔓延时会发生衰减,并在楼梯所在位置出现大幅度温降.在人眼高度处,温度随着与火源中心距离的增加而降低,在楼梯位置处由于烟气沉降导致温度上升.火灾发生后打开B3屏蔽门、开启B3站台排烟系统、B3轨行区排烟系统和B2站台补风系统后,沿楼梯口向下的最大风速为1.4 m/s,此时应加大排烟量,开启区间隧道排烟系统.
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