地铁同站台高架换乘车站火灾全尺寸实验研究—(2)站厅火灾

Full-scale experimental study on fire in one-platform-interchange elevated metro station-(2) station hall fire

为了研究地铁同站台高架换乘车站火灾情况,在地铁同站台高架换乘车站站厅层应急疏散路径关键节点部位开展0.25~0.75 MW规模的全尺寸实验,结合流速、烟气温度和现场观测情况,对自然通风条件下不同部位起火时的火灾危险性进行分析。结果表明:该结构车站站厅火灾危险程度受火源规模、装修形式和通风条件的影响,站厅中部闸机附近起火时,火源阻塞了站厅中部的疏散路径,掺混大量空气的低温烟气在站厅两侧出站闸机处沉降至地面高度;楼扶梯入口处起火时,站内各区域能够形成稳定的烟气分层,人眼高度能见度较高;出入口附近起火时,受自然风的影响,火源下风向区域烟气沉降严重,人眼高度的能见度较低,不利于人员疏散;在实验火灾规模下站厅各区域沉降至危险高度的烟气最高温度为30~41℃。针对此类结构车站站厅的防排烟设计,应综合考虑出入口空间布局和吊顶形式对火灾危险性的影响,利用自然风压形成一定通风换气量,同时,应将掺混空气的低温烟气控制在较小区域内,确保人员疏散路径的能见度和烟气浓度处于安全水平。

To study the fire in the one-platform-interchange elevated metro station,the full-scale experiments with the fire size of 0.25~0.75 MW were carried out at the key node locations of emergency evacuation path on the station hall of the one-platform-interchange elevated metro station,and the fire risk at different fire locations under natural ventilation was analyzed combined with the gas flow velocity,smoke temperature and field observation situation.The results showed that the danger level of station hall fire in the station with this structure was influenced by the fire size,decoration form and ventilation condition.When the fire occurred near the fare gate in the middle of station hall,the fire source blocked the evacuation path in the middle of station hall,and the low temperature smoke mixed with large amount of air descended to the ground level at the locations of fare gate on both sides of station hall.When the fire occurred at the entrance of escalator,the stable smoke layer formulated in each region of station,and the visibility at eye level was relatively high.When the fire occurred near the exits,the smoke descending in the downwind region of fire source was serious under the influence of natural ventilation,and the visibility at eye level was relatively low,which was unfavorable for the personnel evacuation.The maximum smoke temperature at the dangerous height in each region of station hall was 30℃~41℃with the experimental fire size.For the smoke control design of station hall with similar structure,the influence of exits spatial layout and suspended ceiling form on the fire risk should be considered comprehensively,and a certain ventilation rate should be formed by using the natural wind pressure.Meanwhile,the low temperature smoke mixed with air should be controlled in a relatively small region,so as to ensure the visibility and smoke concentration on the evacuation path being in the safe level.