不同结构形式城市地下道路火灾烟气蔓延特性及控制技术

发布时间：2018-03-16 23:13

本文选题：城市地下道路　切入点：坡度　出处：《北京工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：城市地下道路日益成为城市道路的重要组成部分,并且在城市地下道路的建设中,一些特殊的结构形式(岔路、坡道、弯道)越来越频繁的出现。由于城市地下道路内部的结构具有岔路多、弯道多、坡度大等特点,使得其发生火灾时,隧道内的烟气流动更加复杂,而目前关于具有这些异形断面的城市地下道路的烟气流动特性的研究较少。基于此,本文通过数值模拟和试验研究相结合的手段对平直隧道、坡度隧道及曲线隧道内烟气的扩散特及控制技术进行了研究,以便于确定有效的通风及人员安全疏散方案。首先采用数值模拟软件FDS,通过对不同长度的模型和边界是否外扩进行了模拟研究,给出了数值模拟中所建模型的最佳长度和合理边界条件。在此基础上建立了平直隧道模型,对不同火源功率及隧道宽度的平直隧道进行模拟,得到不同工况下的烟气卷吸量沿隧道纵向的分布规律,以便为集中排烟系统排烟量的确定提供参考。针对坡度隧道,通过数值模拟对隧道的坡度和火源功率对烟气扩散特性的影响进行了研究,得到了烟气温度及速度的沿隧道纵向的分布规律,并对其中的温度分布规律进行了试验验证。然后运用数值模拟和比例模型试验的研究手段,对坡度隧道在不同坡度和火源功率下的临界风速进行了确定,并用得到的风速值拟合出坡度隧道临界风速修正公式kg=1+0.0715i。最后对曲线隧道内烟气的扩散特性及纵向烟气控制进行了数值模拟研究。通过改变曲线隧道的半径和弧度及火源功率来研究这些因素对烟气蔓延及控制的影响。结果表明:曲线隧道弧度的改变比半径的改变对于烟气蔓延和控制的影响大。
[Abstract]:Urban underground roads are increasingly becoming an important part of urban roads, and in the construction of urban underground roads, some special structural forms (fork roads, ramps, etc.). Because the structure of the underground road in the city has more and more bifurcations, more bends and large slopes, the flue gas flow in the tunnel becomes more complicated when the fire occurs. However, there are few studies on the flue gas flow characteristics of urban underground roads with these special-shaped sections. The diffusion characteristics and control techniques of flue gas in slope tunnel and curve tunnel are studied. In order to determine the effective ventilation and safety evacuation scheme, the numerical simulation software FDS is used to simulate the model and boundary extension of different lengths. The optimum length and reasonable boundary conditions of the model in numerical simulation are given. On the basis of the model, the model of straight tunnel with different fire source power and tunnel width is established, and the model is used to simulate the straight tunnel with different fire source power and tunnel width. The distribution of flue gas entrainment along the tunnel under different working conditions is obtained in order to provide a reference for the determination of the exhaust volume of the centralized exhaust system. The influence of the slope of tunnel and the power of fire source on the characteristics of flue gas diffusion is studied by numerical simulation. The distribution law of flue gas temperature and velocity along the longitudinal direction of tunnel is obtained. Then the critical wind speed of slope tunnel under different slope and fire source power is determined by means of numerical simulation and proportional model test. The critical wind speed correction formula kg=1 0.0715i. finally, numerical simulation of smoke diffusion characteristics and longitudinal flue gas control in curved tunnel is carried out. The radius and arc of curved tunnel are changed. The influence of these factors on flue gas spread and control is studied. The results show that the change of curve tunnel arc is more important than the change of radius on smoke spread and control.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U492.8

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