高海拔双向行车公路隧道火灾控烟风速研究

雀儿山隧道为高海拔双向行车公路隧道,发生火灾后需要兼顾火灾点两侧人员的疏散,烟气控制较单向行车隧道复杂。采用FDS软件对雀儿山隧道进行火灾三维数值模拟,研究了高海拔双向行车公路隧道火灾时的烟气流动规律和能见度分布规律。研究结果表明:高海拔隧道火灾烟气流动比低海拔隧道速度快;纵坡隧道发生火灾时,若不采取任何控烟措施,烟流在火风压效应的作用下会从高洞口排出,而烟流沿下坡方向的蔓延距离仅在10 m左右,火灾烟气沿火灾点两侧蔓延极不对称;当隧道高洞口控制风速过大或横通道内控制风速过小时,易出现烟气蔓延对称性不佳或烟气窜入横通道,故二者应合理取值;当隧道高洞口施加0.5 m/s的风速、横通道施加1.0 m/s的风速时,烟气在火灾点两侧基本呈对称蔓延,且火灾两侧的能见度也基本对称;建议类似于依托工程的单洞双向行车公路隧道火灾疏散救援阶段,隧道高洞口风速控制在0.5 m/s左右、横通道内风速控制在1.0 m/s左右,以利于人员逃生。

Study on Controlling Velocity under Fire in Two-direction Road Tunnel with High Altitude

The Queershan Tunnel is a two-direction road tunnel with high altitude. Due to the evacuation needed in both directions, the smoke controlling is more complicated than the one-direction tunnels. The FDS software is used to simulate the fire in the Queershan tunnel, and the law of smoke flow movement and the distribution of the visibility in the two-direction road tunnel with high altitude were studied. The results show that the smoke flows faster in high altitude tunnel than that in low altitude tunnel. The smoke flow will be discharged from the high side under the action of the fire pressure effect, while the distance of the smoke flow along the downhill direction is only about 10 m, and the smoke spreads along both sides of the fire spot asymmetrically if no smoke controlling measures are taken in the tunnel fire. When the controlling velocity at the high side is too large or controlling velocities at transverse alleyways are too small, it will be prone to the phenomenon that smoke spreading symmetry is poor or smoke flees into transverse alleyways, so the controlling velocities at the high side and transverse alleyways should be the reasonable value. When the controlling velocity is 0.5 m/s at the tunnel entrance and the controlling velocities are 1.0 m/s at the transverse alleyways, the smoke spread and the visibility are symmetrical on both sides of the fire source. It is suggested that the velocity of high side should be controlled at 0.5 m/s, and the velocities in transverse alleyways should be controlled at 1.0 m/s, so it is the most reasonable situation to escape.