顶部竖井城市隧道火灾模型实验与数值模拟研究

发布时间：2018-03-06 13:32

本文选题：顶部竖井隧道　切入点：自然通风　出处：《中国石油大学(华东)》2015年硕士论文　论文类型：学位论文

【摘要】：当前我国地面交通体系较为发达,但仍无法满足城市的发展要求,交通拥堵现象和交通事故的屡屡发生制约着经济的健康发展。新型顶部竖井城市隧道具有节能环保的优点,但能否满足隧道火灾时的防排烟要求,需要通过实验来验证。本课题开展顶部竖井城市隧道火灾研究,为顶部竖井城市隧道的开口设计和火灾后果预测提供理论支撑。自然通风技术在隧道工程中的应用日益增多,但与机械通风相比,对其防排烟有效性的研究较少。以弗诺德准则数作为隧道火灾模型实验设计的依据,通过理论分析,得到模型率应大于1:15。综合考虑实验条件、可操作性等因素,并通过多次实验和论证,最终确定隧道火灾模型实验设计的相似比为1:10。并搭建了顶部竖井城市隧道模型实验平台。在前人研究的基础上,对火灾烟气运动的发展过程、烟气逆流、烟气层吸穿等现象进行了理论分析,对适合于预测全封闭隧道的顶棚附近最高温升和烟气逆流距离的理论模型进行了修正,使之适用于顶部竖井城市隧道火灾情况。确定一辆汽车发生火灾的事故场景,测量得到对应实际的火源功率为3.16MW,从竖井高度、竖井组间距、竖井数量、相邻竖井间距、竖井宽度等方面研究了竖井设计参数对竖井自然排烟的影响,得到了竖井尺寸参数变化时烟气的运动规律,给出了竖井尺寸设计值的参考范围。运用FDS火灾模拟软件,构建了顶部竖井全尺寸隧道火灾模型,通过与模型实验结果进行对比分析,验证了数值模型的有效性,同时根据竖井的纯烟气排放量,对顶部竖井城市隧道的自然排烟效果进一步分析,发现烟气层吸穿现象是导致竖井自然排烟效率降低的重要影响因素,同时也得到随着竖井高度的增加,纯烟气的排放流量逐渐增加;随着组间距的增大,纯烟气的排放流量先降低后升高;随着竖井宽度的增加,单位面积纯烟气的排放流量呈下降趋势的结论。基于正交实验,对降低顶棚附近最高烟气温升、减小烟气扩散速率、降低烟气沉降速率的竖井组合方案进行分析,得到影响这三方面因子的重要程度,最终确定了顶部竖井优化组合方案。同时根据实验结果和数值模拟结果对顶部竖井城市隧道顶棚附近最高烟气温度和烟气逆流距离理论模型进行了验证。
[Abstract]:At present, the ground transportation system of our country is more developed, but still can not meet the requirements of the development of the city. The phenomenon of traffic congestion and traffic accidents often restrict the healthy development of the economy. The new type of urban tunnel with vertical shaft has the advantages of energy saving and environmental protection. However, whether it can meet the requirements of smoke prevention and exhaust in tunnel fires needs to be verified by experiments. It provides theoretical support for the design of openings and prediction of fire consequences of urban tunnels with vertical shafts at the top. The application of natural ventilation technology in tunnel engineering is increasing day by day, but compared with mechanical ventilation, natural ventilation technology is widely used in tunnel engineering. Based on the theoretical analysis, the model rate should be greater than 1: 15. Considering the experimental conditions, maneuverability and so on, the model rate should be more than 1: 15. Through many experiments and demonstration, the similarity ratio of tunnel fire model design is determined to be 1: 10. The experimental platform of urban tunnel model with top shaft is built. On the basis of previous research, the development process of fire smoke movement is discussed. The phenomena of flue gas countercurrent and smoke layer suction are analyzed theoretically, and the theoretical model suitable for predicting the maximum temperature rise and flue gas countercurrent distance near the roof of a fully closed tunnel is modified. It is suitable for the fire situation of the top shaft city tunnel. The accident scene of a car fire is determined, and the corresponding actual fire source power is 3.16MW. from the shaft height, the spacing of the shaft groups, the number of the shaft, the distance between adjacent shafts, In this paper, the influence of shaft design parameters on the natural smoke exhaust of shaft is studied in terms of shaft width, the movement law of flue gas is obtained when the size parameter of shaft changes, and the reference range of the design value of shaft size is given. The FDS fire simulation software is used. The full-scale tunnel fire model of the top shaft is constructed, and the numerical model is verified by comparing the results with the experimental results. At the same time, according to the pure flue gas emissions from the shaft, the numerical model is proved to be effective. Through further analysis of the natural smoke exhaust effect of the top shaft city tunnel, it is found that the phenomenon of smoke layer penetration is an important factor that leads to the decrease of the natural smoke exhaust efficiency of the shaft, and at the same time, with the increase of the shaft height, The discharge rate of pure flue gas increases gradually; with the increase of group spacing, the discharge rate of pure flue gas decreases first and then increases; with the increase of shaft width, the discharge rate of pure flue gas per unit area shows a downward trend. This paper analyzes the shaft combination scheme of reducing the maximum flue gas temperature rise near the ceiling, reducing the flue gas diffusion rate and reducing the flue gas subsidence rate, and obtains the importance of these three factors. Finally, the optimal combination scheme of top shaft is determined, and the theoretical model of maximum flue gas temperature and flue gas countercurrent distance near the roof of top shaft urban tunnel is verified according to the experimental results and numerical simulation results.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U458

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