摘要
隧道顶板下方烟气的最高温度对隧道防火设计有重要影响。采用FDS对人字坡隧道下游坡度为0、-3%、-5%、-8%、-10%、-12%、-15%等场景进行模拟分析,以探讨人字坡隧道内的烟气分布规律,得出顶板下方最高温度沿程衰减与隧道坡度、火源功率之间的关系。结果表明,随隧道下游坡度增加,上游烟气蔓延速率加快。当燃烧处于稳定状态时,人字坡隧道两端的烟气层始终与水平地面平行,与隧道两端的坡度无关;随隧道下游坡度增加,人字坡隧道的最高温度逐渐增加,其温度明显高于单坡度隧道的温度;当坡度达10%时,温度不再受坡度影响。对数值模拟的数据进行拟合,得出最高温度沿长度方向呈指数衰减,与火源功率呈3/4次方关系,进而建立了最高温度变化的预测模型。
The given paper is to devote itself to the study of the maximum smoke temperature below the roof of the herringbone tunnel fire,which is supposed to have a vital function in the fire safety design of the tunnel. To make an exploration of the impact of the slope of the herringbone tunnel on the maximum temperature and the characteristic features of the fire smoke as well as the distribution specialty of the smoke,we have laid out a numerical simulation experiment to be carried out in the tunnel of 80 m long and 10 m wide with a height of 5 m in their corresponding different downstream-oriented slopes of 0,-3%,-5%,-8%,-10%,-12%,-15%. What is more,we have particularly put our study focus on the smoke movement and the maximum temperature under the ceiling distribution along the tunnel longitudinal axis in hoping to work out the relationship among the fire maximum temperature and the tunnel slope,as well as the heat release rate. The simulation results indicate that,with the increase of the downstream-oriented slope,the spreading rate of the upstream smoke tends to increase,too. In such a case,it would be possible to find a typical smoke movement trend during the quasisteady state： that is to say,the smoke layer interface in the two directions of the herringbone slope tunnel seems to be almost parallel to the horizontal level,even if the slope of the tunnel turns to be more or less changeable. However,the maximum temperature in the upstream direction under the ceiling may tend to drop down progressively with the increase of the distance from the fire source. In addition,with the increase of the downstream slope,the upstream maximum temperature tends to increase gradually,too. Nevertheless,when the slope reaches by a rate of 10%,no longer can the temperature effect be found by the difference of the slope height,though its temperature influence higher than that of the single slope tunnel proves noticeable. Therefore,we have gained the dimensionless relation of the maximum temperature change by fitting the data of the numerical simulation,in which we have taken into account such factors,as the heat release rate,the downstream sloping rate and the distance from the fire source.In turn,the empirical correlation indicates that the dimensionless upstream maximum temperature tends to decay exponentially with the increase of the distance from the fire source in a ratio of 3/4 of the dimensionless heat release,whose relation with the tunnel slope seems to be neither linear nor monotonous. Thus,it can be seen that the derived empirical equations should be of significant usefulness in offering a reference to the fire protection design in the case of herringbone slope tunnels.
作者
姜学鹏
廖湘娟
何振华
JIANG Xue-peng;LIAO Xiang-juan;HE Zhen-hua(School of Resource and Environmental Engineering, Wuhan University of Science and Technology, Wuhan 430081, China;Fire Safety Technology Institute, Wuhan University of Science and Technology, Wuhan 430081, China;Industrial Safety Engi- neering Technology Research Center of Hubei Province, Wuhan University of Science and Technology, Wuhan 430081, China;Tunnel and Underground Space Institute, Central and Southern China Municipal Engineering Design ＆ Research Institute Co. , Ltd, Wuhan 430081, China)
出处
《安全与环境学报》
CAS
CSCD
北大核心
2018年第3期925-929,共5页
Journal of Safety and Environment
基金
公安部消防局科研计划项目(2016XFCX20)
湖北省自然科学基金计划面上项目(2018CFB186,2018CFB226)
中国市政工程中南设计研究总院有限公司课题(KYT-L-2018-001)
关键词
安全工程
人字坡隧道火灾
最高温度
下游坡度
数值模拟
safety engineering
herringbone slope tunnel fire
maximum temperature
downstream slope
numerical simulation
