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为了深入了解沉管隧道火灾过程中烟气的蔓延规律,通过理论推导与足尺试验验证相结合的方法,建立烟气流动的数学模型,推导出烟气层温度及流速沿隧道纵向衰减的理论模型。在此基础上,以港珠澳沉管隧道为研究对象,建立1∶1足尺沉管试验隧道,配备完善的机电系统与测量系统,开展隧道火灾试验,对不同火灾热释放速率和纵向风条件下的烟气层平均温度与平均流速的预测模型进行验证。研究结果表明:在忽略烟气层对下层冷空气的卷吸作用时,烟气温度沿隧道纵向呈指数衰减;同时,烟气蔓延速度的衰减与温度衰减成正比,沿隧道纵向也呈指数衰减。最终给出港珠澳大桥海底沉管隧道火灾工况下烟气运动的预测模型。
In order to understand the flue gas spreading law during immersed tunnel fire deeply, a mathematic model of flue gas flow was established by theoretical derivation and verification by full-scale test. The theory of flue gas layer temperature and longitudinal attenuation along the tunnel was deduced model. On this basis, taking the Hong Kong-Zhuhai-Macao immersed tunnel as the research object, a 1: 1 full-scale immersed tunnel was set up and equipped with a complete mechanical and electrical system and a measuring system to carry out tunnel fire tests. The fire release rates and longitudinal wind Under the conditions of the average temperature of the flue gas layer and the average flow rate of the prediction model to verify. The results show that the flue gas temperature declines exponentially along the longitudinal direction of the tunnel while neglecting the entrainment of the lower layer of cold air in the flue gas layer. At the same time, the attenuation of the flue gas spreading rate is proportional to the temperature decay and exponential decay along the longitudinal direction of the tunnel . Finally, the forecast model of flue gas movement under submerged submerged tunnel of Hong Kong-Zhuhai-Macao Bridge under fire condition is given.