特长公路隧道火灾数值模拟

发布时间：2019-06-26 11:56

【摘要】：对于特长公路隧道,当火灾发生时,隧道内部的烟气扩散特征和诸多因素相关,如隧道纵坡、隧道横截面大小、火源功率大小、阻塞比、纵向通风风速等,不同因素对其烟气运动产生的影响各不相同,根据实际项目自身特点,确定其模拟仿真的数值参数,进行不同因素的影响分析对于分析隧道火灾特征有很重要的现实意义。结合米溪梁特长公路隧道设计参数文件确定PyroSim软件的隧道模型,分析了不同因素对隧道火灾临界风速、温度分布、烟气扩散的影响,发现火源功率越大所需的临界风速越大,当火源功率大于70MW时临界风速增长缓慢,当大于100MW时临界风速维持在4.3m/s不变。随着隧道负坡坡度的增加临界风速显著增大,随着隧道正坡坡度的增大临界风速逐渐减小。阻塞比对临界风速有一定影响。当阻塞比为0~20%时,随着阻塞比的增大临界风速显著下降,由3.2m/s降到2.6m/s;当阻塞比为20%~40%时,随着阻塞比的增大,临界风速缓慢下降由2.6m/s降为2.4m/s,当阻塞比大于40%时,对临界风速基本没有影响。火灾发生时,隧道纵向温度分布呈先升高后减小的变化趋势,火源附近的温度梯度也是先增大后减小,通风和纵坡条件下,温度最高断面逐步向下游移动,出现最高点温度漂移现象。在坡度绝对值小于1.0%时浮力效应不太明显,在坡度大于等于1.5%时随着坡度的增大隧道的浮力效应比较明显,"烟囱效应"形成。
[Abstract]:For extra-long highway tunnel, when the fire occurs, the smoke spreading characteristics in the tunnel are related to many factors, such as the tunnel longitudinal slope, the tunnel cross-section size, the fire source power, the blocking ratio, the longitudinal ventilation wind speed and the like, and the influence of different factors on the smoke movement of the tunnel is different, Based on the characteristics of the actual project, it is of great practical significance to determine the numerical parameters of the simulation and to analyze the influence of different factors on the analysis of the fire characteristics of the tunnel. The tunnel model of the PyroSim software is determined by combining the design parameters of the Moxi-beam super-long highway tunnel, and the influence of different factors on the critical wind speed, the temperature distribution and the smoke diffusion of the tunnel fire is analyzed, and the larger the critical wind speed required by the larger the power of the fire source is found, The critical wind speed increases slowly when the power of the fire source is greater than 70MW, and the critical wind speed is maintained at 4.3 m/ s when it is more than 100 MW. With the increasing of the slope of the negative slope of the tunnel, the critical wind speed is obviously increased, and the critical wind speed is gradually reduced as the slope of the slope of the slope of the tunnel is increasing. The blocking ratio has a certain effect on the critical wind speed. When the blocking ratio is 0-20%, the critical wind speed is reduced to 2.6m/ s with the increase of the blocking ratio, and when the blocking ratio is 20-40%, the critical wind speed decreases from 2.6 m/ s to 2.4 m/ s, and when the blocking ratio is greater than 40%, the critical wind speed has no effect. In the case of fire, the longitudinal temperature distribution of the tunnel is decreased after the first increase. The temperature gradient in the vicinity of the fire source is also reduced after the first increase, and the highest temperature section of the temperature gradually moves to the downstream under the conditions of the ventilation and the vertical slope, and the temperature drift of the highest point occurs. The buoyancy effect is less obvious when the absolute value of the slope is less than 1.0%, and when the slope is greater than or equal to 1.5%, the buoyancy effect of the tunnel increases with the increase of the slope, and the "chimney effect" is formed.
【作者单位】：长安大学公路学院;陕西省交通规划设计研究院;
【分类号】：U458

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