封堵条件对倾斜隧道火灾顶棚温度分布的影响

Influence of sealing conditions on the temperature distribution under the tunnel ceiling in inclined tunnel fires

采用小尺寸试验的研究方法,考虑不同封堵条件、火源热释放速率和隧道坡度的影响,研究了高、低端出口封堵对倾斜隧道火灾烟气扩散和隧道顶棚温度分布的影响。结果表明:当隧道低端出口封堵时,烟气层近似与隧道底板平行,顶棚最高温升受隧道坡度的影响较小。当隧道高端出口封堵时,烟气层交界面近似水平,顶棚最高温升随隧道坡度的增大而升高。两种封堵条件下,倾斜隧道火灾顶棚纵向温度分布在隧道开敞侧均呈指数衰减。隧道高端出口封堵时,坡度对顶棚温升衰减规律特性的影响较大。相反,坡度对低端出口封堵隧道顶棚温升衰减规律特性的影响较小。综合考虑封堵条件、热释放速率和隧道坡度的影响,建立了最高烟气温升和顶棚温度纵向衰减的预测模型。

The model-scale experiment method was used to study the fire smoke diffusion and temperature distribution under the ceiling in an inclined tunnel with the upper or lower portal sealed,considering different sealing conditions,heat release rates and tun-nel slopes.The results show that when the lower portal is sealed,the smoke layer is approximately parallel to the tunnel floor,and the slope has little effect on the maximum temperature rise.When the upper portal is sealed,the smoke layer interface is almost par-allel,and the maximum temperature rise increases with the tunnel slope.The longitudinal temperature distribution under the ceiling in inclined tunnel fires exhibits exponential decay under different sealing conditions.The tunnel slope has a great influence on the temperature decay under the ceiling in upper-portal-sealed tun-nels.On the contrary,the slope has little influence on the longitu-dinal temperature decay in lower-portal-sealed tunnels.Finally,some comprehensive empirical formulas are established to esti-mate the ceiling maximum temperature rise and the temperature decay taking sealing conditions,heat release rates and tunnel slopes into consideration.