针对自然通风的半敞开式城市隧道火灾时不能充分保障人员安全疏散的问题,文章运用Fire Dynamic Simulation (FDS)火灾模拟软件及风洞实验台对城市隧道火灾在自然通风和混合式通风两种不同模式下的烟气扩散情况进行了数值模拟和实验研究. 结果表明,半敞开式城市隧道自然通风不能有效解决火灾的安全问题;而当排烟系数在3.3左右时,混合式通风能实现烟气的有效控制,保证了人员及车辆的安全疏散.采用本文提出的排烟系数研究半敞开式城市隧道的混合通风模型,可以为该类隧道的火灾安全防范提供一定的理论依据.%Aimed at the problem of not being able to fully guarantee safe evacuation in case of urban tunnel fires with semi-open natural ventilation, the Fire Dynamic Simulation (FDS) software and a wind tunnel experimental platform were used to carry out a numerical simulation and experimental study on how smoke diffuses under nat-ural ventilation and hybrid ventilation modes. The results show that natural ventilation used in a semi-open urban tunnel is unable to solve the problems of fire safety, but hybrid ventilation can effectively control smoke when the exhaust coefficient reaches 3.3, which assures the safe evacuation of personnel and vehicles. Additionally, the ex-haust coefficient presented in this paper and applied in the study of the hybrid ventilation mode for semi-open urban tunnels may provide a theoretical basis for similar tunnels regarding safety during fires.
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