受限空间建筑火灾蔓延影响因素对比试验研究

Comparative experimental study on factors affecting fire spread in enclosed buildings

为观测受限空间建筑火灾蔓延时空演化规律,了解受限空间建筑火灾蔓延过程,建造了一座二层2×2跨的钢框架结构建筑,其中在一层设置四个房间,采用木垛作为火荷载开展受限空间建筑火灾蔓延试验。考虑火荷载、分隔构件、开口程度3个因素,共设置4种工况。试验中采用摄像机观测火灾蔓延过程,采用热电偶记录建筑内部空间温度场,基于耗氧法记录受限空间建筑火灾蔓延热释放速率。结果表明:火灾过程中火灾轰燃前持续时间较长,占火灾蔓延前持续时间的70%~85%,火灾轰燃后火势迅速增大并在短时间内蔓延至相邻房间,火灾蔓延时刻热释放速率约为轰燃时刻的1.5~4倍;受限空间建筑火灾蔓延在空间上表现为由不均匀温度场向均匀温度场过渡,在时间上表现为火灾蔓延速度逐渐增加;目标房间温度场在火灾蔓延前相比着火房间温度场存在一定程度的折减;局部火荷载密度、火荷载总量越大,越有利于火灾蔓延;开口程度会影响房间之间的烟气蔓延;分隔构件会阻碍烟气流动及火焰传播,显著影响火灾蔓延过程。

To observe the fire spread spatiotemporal evolution within enclosed buildings and explore the fire spread process,a two-storey 2x2 moment-resisting steel framed structure was constructed.Four rooms were arranged on the first floor,and wood cribs were employed as the fire load.Four distinct scenarios were considered based on fire load,compartment elements and opening size.During the experiment,the fire spread process was observed by the camera,the gas-phase temperature field was recorded by thermocouples,and the heat release rate was measured based on oxygen-consumption method.The experiment reveals that the pre-flashover stage during the fire process has a significantly prolonged duration,accounting for 70%-85%of the total fire spread time.The fire rapidly intensifies in the post-flashover stage and propagates to adjacent rooms within a short timeframe.The heat release rate at fire spread stage is approximately 1.5 to 4 times that at the flashover stage.The findings indicates that the spread of fire in confined space buildings manifests itself as a transition from an uneven temperature field to a uniform temperature field in space,and as a gradual increase in the fire spread rate in time.Before the fire spreads,the temperature field of the target compartment is reduced to a certain extent compared to the temperature field of the fire room.Local fire load density and total fire load exhibit positive influences on enclosed fire spread.Opening size influences smoke propagation between compartments,and compartment elements barriers hinder smoke flow and flame propagation,which significantly affects the fire spread process.