【作者】 黄昂；

【导师】 徐志胜；

【作者基本信息】 中南大学 ， 防灾减灾工程及防护工程， 2010， 博士

【摘要】 随着工业自动化进程的加剧,联合工房在卷烟行业中得到了广泛的应用。由于难以满足防火分隔要求,卷烟生产联合工房的出现给建筑火灾防治研究带来了新的问题。本文针对卷烟联合工房的可燃物燃烧特性、火灾烟气流动与控制、人员疏散模拟以及屋顶钢网架结构的整体抗火性能分析方法开展了理论和试验研究,完成的工作以及获得的主要成果如下：(1)采用锥形量热仪对烟草可燃物的燃烧特性进行了测试。烟草可燃物试样在燃烧过程中峰值热释放速率处于20-100 kW/m2范围,平均热释放速率处于10-50 kW/m2范围；由于形态和质地的不同,烟丝和烟叶热释放速率增长介于中速t2火与慢速t2火之间,而烟梗的热释放速率增长要低于慢速t2火；烟丝的燃烧完全程度较高,但燃烧时烟气中含有较多的固体物。(2)建立了顶棚射流和反浮力壁面射流的数学模型。在适当简化的基础上,对流动控制方程组进行了数值求解,获得了烟气温度、速度以及厚度随位置变化的关系曲线。利用试验结果与模型计算结果进行对比,在合理参数的选择范围内,验证了模型的有效性。(3)采用数值模拟方法对缩尺寸模型试验的可行性进行了研究。利用缩尺寸模型试验方法对卷烟联合工房火灾的烟气自然充填、自然排烟和机械排烟过程进行了研究,获得了不同烟气控制方式下室内温度和烟气层界面高度分布。试验结果表明：火灾条件下,室内温度具有明显的分层现象,然而由于受局部流动的影响,室内不同位置处的烟气层界面高度并不相同,靠近壁而附近的烟气层更低,易对人员疏散造成影响。基于反浮力壁面射流的特点,提出了抑制疏散口附近烟气沉降过快的两种方法。(4)提出了人员疏散的移动速度控制和出口宽度控制的两种疏散模式。给出了两种模式的判据以及人员疏散时间计算方法。对火灾影响下人员行为的量化表达式开展了研究,给出了火灾对人员移动速度、人员疏散响应时间和出口通行能力影响的定量关系式。建立了联合工房火灾人员疏散的计算模型,并对一个实际联合工房进行实例计算。卷烟联合工房内的人员疏散属于移动速度控制模式,疏散口不会出现拥堵。(5)根据火灾条件下网架结构的破坏准则,提出了钢网架结构整体抗火性能分析方法和步骤流程。以一实际工房为模型进行实例计算,计算表明,火灾条件下的结构安全应对构件的传热过程以及结构自身的受力、约束条件进行综合分析,不应单以结构的受热环境作为判断结构抗火性能评判的唯一指标。卷烟联合工房火灾的防治是一个有机的系统工程,涉及多个学科理论和工程应用的交叉,本文的研究将对该类建筑的防火设计提供理论和数据参考。更多还原

【Abstract】 Along with the improvement of automation in industry, joint workshops are more and more widely used in tobacco industry. However, application of joint workshop brings new challenge to fire protection of building because of difficulties in fire compartmentation. Theoretical and experimental analysis are carried out to study characteristics of combustibles, smoke movement and control, evacuation, and fire-resistance of grid structure of steel of tobacco joint workshop in this dissertation. Achievements of this study are listed as the following:(1) Characteristics of tobacco combustibles are studied using cone-calorimeter. Maximum heat release rate of samples of tobacco combustible is 20-100 kW/m2 and average heat release rate is 10-50 kW/m. Increase rate of heat release rate of tobacco leaves and threads fire is between that of slow t-square fire and medium t-square fire, and increase rate of heat release rate of tobacco sticks is less than that of slow t-square fire, since there are great differences in form and texture between tobacco leaves, threads and sticks. The combustion efficiency of tobacco thread is high, while there is considerable dust in the smoke.(2) Mathmatic models for ceiling jet and wall jet with negative buoyancy are proposed. Numerical solutions for the models are provided for the models based on simplification. Variation of smoke depth, temperature and velocity along with the coordinates are obtained. Experimental results are used to compare with the predictions of mathematic models, good agreements are observed(3) Reduced-scale experiments are performed to study smoke filling in a model joint workshop with natural ventilation and mechanical exhaust. Profiles of temperature and smoke layer height are obtained. It is demonstrated from the experimental results that there is evident stratification of temperature in the model workshop under fire. However, smoke layer height varies with positions because of the effect of local flow such as ceiling jet and wall jet. Smoke layer heights near wall are lower than other position because of the wall jet with negative buoyancy, which results in affecting the evacuation at the exits. Based on the characterics of wall jet with negative buoyancy, two means are proposed to weaken the influence of wall jet.(4) 2 modes of evacuation (personnel-pace-control mode and exit-width-control mode) are proposed to describe the evacuation in building, criterion and calculation of evacuation time of 2 modes are also provided. Quantitive study on effect of fire on personnel movement, pre-action time and flow capacity of exit are performed. Case simulation with a factual workshop is carried out, which shows that the mode of evacuation in joint workshop is personnel-pace-control and there are barely jam at the exits.(5) According to the breakage criterion of steel structure, method and process for risk assessment of grid structure of steel under fire is proposed. Case study with a factual workshop roof is performed and it is showed that risk assessment of grid structure of steel under fire should combine conditions of fire, heat transfer with conditions of loading, geometrical restriction of the structure itself. Considering the heating condition of structure under fire merely is not enough to judge the reliability of structure.It is a systematic project of fire protection of tobacco joint workshop. A number of theoretical and engineering subjects are involved. Therefore, the study in this paper is helpful to fire protection design of tobacco joint workshop with the theoretical models and experimental data.更多还原