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城万二级公路白芷山隧道和八台山隧道为双向行车的大纵坡公路隧道,火灾后烟流控制难。采用火灾动力学计算软件FDS对其进行了火灾三维数值模拟,分析了仅火风压作用及0.5 m/s、1 m/s和-0.5 m/s控制风速作用下的烟流扩散和能见度的分布规律。结果表明:在大纵坡隧道中,火灾后仅靠火灾效应能引起火灾烟流的流动,其流动的规律是烟流从火源点流向高洞口方向,火灾烟流能完全从高洞口排出,而烟流向火源点下坡方向的蔓延距离仅在100 m左右;当风速为0.5 m/s时,烟流在火源两侧基本呈对称状蔓延;下坡方向的隧道中的烟流也因风速较小,产生的扰动比较小,这种烟流控制是最为合理,有利于灾害情况下逃生。因此,建议将白芷山隧道和八台山隧道的火灾控制风速取为0.5 m/s左右,且该速度应为自然风速、火风压引起的风速和风机提供风速的合速度。
The tunnels of Baihe Mountain Tunnel and Baitaishan Tunnel of Chengwan Grade II Highway are two-way traffic high-speed highway tunnels, and the smoke flow control after fire is difficult. The fire dynamics calculation software FDS was used to simulate the three-dimensional fire and the fire diffusion and visibility under the action of only the air pressure and the control wind speed of 0.5 m / s, 1 m / s and -0.5 m / s were analyzed. Distribution. The results show that in large longitudinal tunnels, the fire smoke flow can only be caused by the fire effect after the fire. The law of the flow is that the smoke flows from the fire source point to the high hole, and the fire smoke flow can be completely discharged from the high hole. While the distance of smoke flow to the descent direction of the fire source is only about 100 m. When the wind speed is 0.5 m / s, the smoke flow basically spreads symmetrically on both sides of the fire source. The smoke flow in the downhill direction also Because of the small wind speed, the disturbance generated is relatively small. This kind of smoke flow control is the most reasonable and is conducive to escape under disaster conditions. Therefore, it is suggested that the fire control wind speed of Baizhishan Tunnel and Baizaishan Tunnel should be about 0.5 m / s, and this speed should be natural wind speed, wind speed caused by fire pressure and wind speed provided by fan.