房顶破拆时间对木结构吊脚楼火灾热释放速率的影响分析

Effect of roof demolition time on heat release rate of the vernacular pillar-supported dwelling

侗族村寨在应对吊脚楼火灾时,有拆屋顶减灾的做法.通过FDS软件对吊脚楼房顶破拆的防火过程进行数值模拟研究.研究结果表明:与有房顶的吊脚楼相比,没有房顶的吊脚楼的最高热释放速率降幅可达到38.2%,且火灾发展过程明显减缓;在4 m处、350 s之前破拆工况的热通量峰值与500 s之后破拆工况的热通量峰值的比值为0.434,峰值最大降幅达56.6%;破拆房顶的最佳时间为火势蔓延到顶层前,火势蔓延到顶层后获得充分发展,破拆失去防火意义.

Villages of Dong ethnic group have the practice of removing the roof of the wood structure building for fire relief.In this paper,the numerical simulation of the roof demolition process was conducted.The results show that with the fire prevention measure,the maximum heat release rate can decrease by 38.2%,and the fire development process can be slowed down obviously;at 4 m,the ratio of the peak heat flux of the demolition condition before 350 s to the peak heat flux of the demolition condition after 500 s is 0.434,and the maximum reduction of the peak value is 56.6%;the best time for the roof demolition is before the spreading of fire to the roof.