【作者】 袁中原；

【导师】 雷波；

【作者基本信息】 西南交通大学 ， 供热、供燃气、通风及空调工程， 2012， 博士

【摘要】 区间隧道采用顶部开孔方式实现自然通风是一种新的地铁通风方式,这种通风方式不仅可以节约地铁列车正常运营的区间隧道换气通风能耗,还可节省通风设备的投资。从工程应用的角度,采用这种通风方式需要明确的一个重要问题是：如何以最少的开孔满足火灾排烟和通风换气要求。本文针对火灾排烟问题,采用理论分析、模型试验和三维数值模拟结合的方法,对顶部开孔地铁区间隧道的火灾烟气特性和烟气控制方法进行了详细、系统、深入的研究,研究成果可以进一步完善自然通风隧道火灾的理论,同时可为自然通风地铁区间隧道火灾控制提供理论支撑。应用国外相关火灾烟气控制标准NFPA130和PIARC制定了顶部开孔的地铁区间隧道发生火灾时的烟气参数控制标准,并且通过理论推导的方法得到了隧道内烟气综合能见度的表达式。同时,对水平单洞双线隧道火灾自然通风时的羽流特征进行了详细的分析,在此基础上通过火灾理论分析方法定义了隧道烟气流量、烟气温度和烟气浓度的无量纲量,并根据烟气参数无量纲量的定义式得到了烟气流量与烟气温度和烟气浓度之间的关系。开展模型隧道火灾试验和全尺寸隧道三维数值计算模拟,详细、系统的研究了火源热释放率、隧道断面、隧道坡度、隧道吊墙、孔口间距、孔口尺寸、火源位置、列车阻塞、初始活塞风等因素对顶部开孔的地铁区间隧道火灾时隧道内烟气扩散特性的影响。烟气扩散特性的研究结果表明：由于孔口的排烟作用,隧道纵向烟气参数在孔口处会发生突变；隧道顶壁的烟气温度在整个隧道纵向方向上均呈下降趋势,而顶壁的烟气浓度仅在火源段呈下降趋势,在非火源段的纵向方向上几乎为定值；隧道内的烟气层厚度在火源段内的纵向方向上几乎为定值,而在非火源段内经历了先升高后降低直至为0的过程；影响人员逃生安全疏散的烟气参数为隧道顶壁烟气温度和隧道内人员高度处的能见度。火源热释放率对烟气参数的无量纲量和烟气层厚度均没有影响,这说明本文定义的烟气参数无量纲量适用于地铁自然通风隧道火灾；列车阻塞和初始活塞风对隧道火灾烟气特性的影响较小；隧道断面、隧道坡度和隧道吊墙会影响到整个隧道的烟气特性参数,而孔口尺寸和孔口间距仅对非火源段内的烟气特性参数以及通风孔口排烟造成影响,不会影响到火源段内的烟气特性参数。采用三维数值模拟计算方法研究了全尺寸隧道火灾时,列车在隧道内的位置、火源在车厢内的位置以及着火车厢在列车中的位置对火灾烟气特性的影响,结果表明隧道发生火灾时的最不利火灾位置为：列车最外侧门窗的外侧边位于某隧道段的孔口内侧边正下方,火源位于着火车厢相应的最外端。根据模型试验隧道和全尺寸隧道的烟气扩散特性,结合隧道火灾的理论分析方法得到了描述顶部开孔地铁区间隧道火灾特性的理论计算模型,包括：隧道顶壁烟气温度纵向衰减模型、孔口排烟量及排烟温度模型、隧道烟气温度分布模型、烟气扩散长度模型、烟气临界距离模型、隧道烟气能见度分布模型等。基于隧道火灾烟气扩散特性的研究结果以及火灾理论计算模型,建立了一套适用于地铁区间隧道火灾自然通风的工程设计方法,具体为：单线隧道由于隧道断面狭小,不适宜采用顶部开孔的自然通风方式；隧道不设置吊墙时,当距离火源30m以外的隧道顶壁最高烟气温度大于180℃时,通风孔口内边距宜取为30m,当此温度小于180℃时,通风孔口内边距宜取为50m～140m；隧道设置吊墙时,通风孔口内边距宜取为130m～220m；通风孔口内边距与长度之间的关系式可按相应的计算模型确定。更多还原

【Abstract】 Natural ventilation by setting openings at the top of the tunnel section is a new way of subway ventilation, which not only save the energy consumption of ventilation in the tunnel section, also save the investment of ventilation facility. From the point of engineering application, the important issues for this ventilation method is how to meet the requirement of fire smoke and ventilation by setting the minimum opening numbers. In this paper, theoretical analysis, reduced-scale experiment, and numerical simualtion method were carried out to investigate the smoke diffusion characteristics and smoke control. This research can further improve the theory of natural ventilation in the tunnel section and also provide theoretical support for fire control standards for natural ventilation in the tunnel section.The smoke control criterion NFPA130and PIARC were adopted to constitute the smoke control standard in tunnel fires with natural ventilation and the integrated visibility was obtained from theoretical analysis. The fire plume characteristics in horizontal tunnel was derived and then the dimensionless smoke flow, smoke temperature and smoke concentration were defined based on the plume characteristics. From the definition of these dimensionless smoke parameters, the relationship between smoke flow and smoke temperature or smoke concentration were developed.The experimental tests in reduced-scale tunnel and numerical simulation in full-scale tunnel were carried out to investigate the effect of some factors on smoke diffusion characteristics such as:heat release rate, tunnel cross-section, tunnel gradient, smoke curtain, shaft distance, shaft size, fire location, train blockage, piston wind and so on.The results of smoke diffusion characteristics in tunnel fire with natural ventilation showed that the smoke parameters changed sharply under the shaft as the smoke exhaust through natural ventilation shaft. The ceiling temperature presented the decrease trend in the longitudinal direction in tunnel, while the ceiling concentration presented the decrease trend in the longitudinal direction in fire section of the tunnel and had almost the same value in non-fire section. In fire section, the thickness of smoke layer were almost the same, while in non-fire section the parameter increased firstly and then decreased to0with the distance from fire source increase. In tunnel fires with natural ventilation, the ceiling temperature and visibility at the height of people head could make a danger, while the rest of smoke parameters didn’t play the role in passenger escape. The heat release rate didn’t have the effect on the dimensionless smoke parameters and the thickness of smoke layer, which indicates the definition of dimensionless parameters were reasonable in tunnel fires with natural ventilation. The train blockage and piston wind didn’t have the significant effect on smoke parameters in tunnel. However the tunnel cross-section, tunnel gradient and smoke curtain had the very significant effect on smoke parameters in tunnel. Moreover, the shaft distance and shaft size could affect the smoke parameters in non-fire section of the tunnel, but didn’t have the significant effect on smoke parameters in fire section.The3-d numerical simulation was used to investigate the worst fire location in full-scale tunnel through the study on train location, fire source location in the carriage and the carriage location in the train. The result showed that the worst fire location was that the widest boundary of door or window in the train was under the inner boundary of the shaft and the fire source located the related boundary in the fire carriage.Based on the smoke diffusion characteristics in reduced-scale tunnel and full-scale tunnel, the theoretical analysis method was adopted to develop the formulas to predict the smoke diffusion characteristic in tunnel fires with natural ventilation. The formulas include ceiling temperature decay, smoke exhaust from shaft, smoke temperature distributions, smoke diffusion distance, critical smoke diffusion distance, the visibility in tunnel and so on.On the basis of smoke diffusion characteristics and the model from theoretical analysis, the engineering design method was established for subway tunnel fires with natural ventilation. The way of natural ventilation couldn’t be used in the single-line tunnel as the small tunnel cross-section. In the tunnel in which the smoke curtain was not set up, the shaft distance of30m is reasonable when the ceiling temperature at the distance from fire source was beyond180℃, while the shaft distance ought to be selected in the range of50m to140m when the ceiling temperature was less180℃. Moreover, in the tunnel in which the smoke curtain was set up, the shaft distance ought to be select in the range of130m to220m. The relationship between the shaft distance and the minimum shaft length could be obtained from the related formulas.更多还原