重点排烟坡度隧道纵向机械补风量研究

Longitudinal Mechanical Air Supply for the Central Smoke Extraction System on Slope Tunnel Fire

合理的纵向机械补风量,可有效保障重点排烟隧道火灾烟气控制效果。基于有效排烟和人员疏散安全两大原则,将烟气蔓延长度、最小清晰高度处能见度以及排烟效率作为判定合理纵向机械补风量的关键性判据。采用FDS6.2对1%、3%和6%坡度隧道下不同排烟量和补风量组合下的80组工况进行模拟计算。结果表明:当隧道坡度为1%、3%和6%时,机械补风量分别占排烟量的50%~70%、70%~100%及90%~120%;坡度小于1%时,坡度隧道与水平隧道的合理补风量和排烟量间比例关系基本一致,当坡度大于1%时,两者合理比例关系随坡度的增大呈现线性增长趋势,与水平隧道时相比其坡度修正系数KQ可取0.8+0.2λ。

Reasonable longitudinal mechanical air supply can effectively guarantee the fire smoke control effect of the central smoke extraction system. Based on the two principles of effective smoke extraction and evacuation safety.Three evaluation indexes are proposed in order to judge the reasonable longitudinal mechanical air supply,and they are smoke spread distance,the visibility distribution at a minimum clear height of the tunnel and smoke—exhaust efficiency. Dynamics Simulation(FDS 6.2) is employed to run numerical simulations based on the three slope tunnel,which are 1%,3% and 6%. Eighty groups of fire conditions with different smoke extraction volumes and air supply volume combinations are simulated. The results of the simulation indicate that the reasonable proportion of air supply volume to smoke extraction volume should be 50% ~ 70%,70% ~ 100% and 90% ~ 120 when the tunnel slope is 1%,3% and 6%. When the slope is less than 1%,the reasonable proportion of air supply volume to the smoke extraction volume of the slope tunnel is basically consistent with the horizontal tunnel. When the slope is greater than 1%,the reasonable proportion relationship shows a linear growth trend with the increase of slope. Compared to the horizontal tunnel,Its slope correction coefficient(KQ) is desirable for 0.8+0.2λ.