燃气爆炸事故对住宅建筑的破坏

目前燃气爆炸事故灾后调查中,尚缺乏有关其破坏机理及特点方面的研究。介绍了发生于上海的2起燃气爆炸事故的概况及处理方案。运用理论计算、数值模拟等方法得出了2起事故中破坏较为严重的预制板和现浇板的抗爆能力,估算出2起事故的爆炸超压。分析了2起事故爆炸超压相差不大,但破坏后果却相差较大的原因。进而对燃气爆炸对房屋造成损坏的特点进行了分析,认为：1）双向现浇板的抗爆能力要远优于单向预制板;2）点火源所在房间直接受到超压波的冲击作用而破坏最为严重,周围房间的破坏则是由震动引起的,距离爆炸点越远影响越小。     

半封闭受限空间煤尘与瓦斯耦合爆炸研究

煤尘参与的瓦斯爆炸事故具有很强的破坏性和伤害性,是煤矿的重大事故之一.用一端开口的半封闭管道爆炸实验装置,通过改变瓦斯与煤尘耦合爆炸浓度及点火条件,揭示受限空间瓦斯与煤尘耦合爆炸的规律.实验结果表明,封闭下的耦合体爆炸火焰传播速度较开口状态达到极值快,但极值点距点火位置较近,开口爆炸火焰传播距离是积聚耦合体长度的2倍左右;瓦斯参与的煤尘爆炸,爆炸相对强度随瓦斯浓度的增加而增加,传播距离更远;理论推导瓦斯与煤尘耦合爆炸超压传播距离与爆炸能量的平方根成正比,与巷道断面积的平方根成反比,研究结果为防治瓦斯爆炸、事故勘验以及阻隔爆装置的研制提供了可靠的实验数据.     

Simulation Analysis of Indoor Gas Explosion Damage

The influence factors and process of indoor gas explosion are studied with AutoReaGas explosion simula-tor. The result shows that venting pressure has great influence on the indoor gas explosion damage. The higher the venting pressure is, the more serious the hazard consequence will be. The ignition location has also evident ef-fect on the gas explosion damage. The explosion static overpressure would not cause major injury to person and se-rious damage to structure in the case of low venting pressure (lower than 2 kPa). The high temperature combus-tion after the explosion is the major factor to person injury in indoor gas explosion accidents.     

长持时爆炸冲击波产生方法

不同持时的爆炸冲击波对建筑结构及防护工程的作用显著不同,在试验或数值模拟中常需要得到长持时爆炸冲击波,延长爆炸冲击波正压作用时间是研究长持时爆炸荷载下结构响应的难点。在AUTODYN中建立长筒爆室小当量炸药多点延时起爆模型,分析爆炸冲击波在长筒爆室中的传播规律,研究管道长度、延时起爆时差、起爆顺序对冲击波波形的影响。结果表明：距离增加,超压峰值减小、正压持续时间增加;根据炸药量和爆室长度合理地选择起爆时差可以获得波形丰满且连续衰减的超压时程曲线;爆室底部起爆、合理控制延时间隔,可以形成类似于大当量远距离爆炸下产生的连续衰减的长持时冲击波。分别给出100、200 ms爆炸持时起爆方案,为长持时爆炸模拟装置的设计提供技术支持。     

基于FLACS的食堂天然气泄漏爆炸事故后果模拟

针对食堂的特点,利用FLACS软件对某大学食堂进行三维建模,在考虑喷射方向、障碍物等因素的基础上,模拟天然气的泄漏及爆炸情况,研究了特定场景下气体云团的扩散过程、爆炸冲击波和温度的发展规律。结果表明,当天然气垂直向上泄漏时,因食堂屋顶的阻碍作用,天然气在小型摊位发生堆积;当天然气水平泄漏时,天然气在用餐区域体积分数较高;爆炸初期,首先出现以点火点为中心的爆炸压力冲击波,压力冲击波以圆弧形向外传递,泄漏方向对爆炸产生的最大超压影响较小;温度分布受泄漏方向的影响较大,垂直喷射时高温集中在小型摊位处,水平喷射时温度沿喷射方向由高到低分布。     

Vacuum chamber suppression of gas-explosion propagation in a tunnel

To control and reduce the harm of a gas explosion, a new method is proposed for suppressing gas-explosion propagation in a tunnel by using a vacuum chamber. We studied the suppression effect on gas explosions by placing a vacuum chamber at dif-ferent positions along the tunnel. The results indicate that: 1) the vacuum chamber can absorb the explosion wave and explosion energy as much as possible at the beginning of the gas explosion, and; 2) when the vacuum chamber is used the closer it is to the ignition source the more significant the suppression effect. In addition, by using the vacuum chamber: 1) the flame propagation velocity decreases from ultrasonic to subsonic; 2) the flame propagation distance is remarkably shortened; 3) the maximum peak value of overpressure (Pro) decreases from 0.34 to 0.17 MPa or less, and; 4) the impulse of the blast wave (/) decreases from 20 to 8 kPa-s or less.     

天生桥二级水电站事故检修闸门动水下门试验

采用局部正态模型,利用计算机模拟结果作为模型的进出口边界条件,试验研究了天生桥二级水电站调压井事故检修闸门在动水关闭过程中调压井和压力钢管内的水流流态、通气管风速、悬吊闸门的钢索拉力、闸后压力钢管内压力变化特性.试验表明:在下门过程中,压力钢管内的水流流态平稳,压力钢管内压力和通气管内风速的峰值与下门速度成线性关系,钢索拉力与下门速度关系不明显;压力钢管内负压和通气管风速在随时间的变化过程中都出现了双峰现象;与压力钢管内负压峰值出现时刻相比,通气管风速峰值存在一定"延迟".试验结果为确定事故检修闸门的下门速度提供了依据.     

Experimental Study on Single Ignition Characteristics of Mixed Solid and Liquid Fuel

In order to probe into the single ignition characteristics of mixed solid and liquid fuel, optical and electrical experinments on unconfined volume dispersion and single ignition of few dosage of ternary fuel mixture are successfully done. Experimental results show that cloud detonation is distinguished from explosion of trinitrotoluene charge. The single ignition process of mixed fuel containing aluminum powder（Al）, propylene oxide （PO） and explosive （TNT） can be divided into four stages, the overpressure within its explosion field first increases, then decays with increase of distance. Explosion effects can be enhanced with adding proper trinitrotoluene into fuel mixture, the optimized ratio is m （Al） ： m （PO）： m （TNT） - 55：35： 10. The overpressure of binary mixed fuel containing Al and TNT decays like trinitrotoluene charge with increase of distance, but its value is higher than the trinitrotoluene charge＇s in the same mass at longer distance. The continual action time of plus overpressure during cloud detonation reaches magnitude of 10 ms and is about 100 times longer than the trinitrotoluene charge＇ s.     

Numerical simulation for explosion wave propagation of combustible mixture gas

A two-dimensional multi-material code was indigenously developed to investigate the effects of duct boundary conditions and ignition positions on the propagation law of explosion wave for hydrogen and methane-based combustible mixture gas. In the code,Young’s technique was employed to track the interface between the explosion products and air,and combustible function model was adopted to simulate ignition process. The code was employed to study explosion flow field inside and outside the duct and to obtain peak pressures in different boundary conditions and ignition positions. Numerical results suggest that during the propagation in a duct,for point initiation,the curvature of spherical wave front gradually decreases and evolves into plane wave. Due to the multiple reflections on the duct wall,multi-peak values appear on pressure—time curve,and peak pressure strongly relies on the duct boundary conditions and ignition position. When explosive wave reaches the exit of the duct,explosion products expand outward and forms shock wave in air. Multiple rarefaction waves also occur and propagate upstream along the duct to decrease the pressure in the duct. The results are in agreement with one-dimensional isentropic gas flow theory of the explosion products,and indicate that the ignition model and multi-material interface treatment method are feasible.     

Effect of variation in gas distribution on explosion propagation characteristics in coal mines

In order to investigate the effect of variation in the distribution of gas on explosion propagation characteristics in coal mines, experiments were carried out in two different channels with variation in gas concentration and geometry. Flame and pressure transducers were used to track the explosion front velocity. The flame speed (Sf) showed a slight downward trend while the methane concentration varied from 10% to 3% in the experimental channel. The peak overpressure (Pmax) dropped dramatically when com-pared with normal conditions. As well, the values of Pmax and Sf decreased when the methane concentration dropped from 8% to 6%. The flame speed in the channel, connected to a cylinder with a length varying from 0.5 to 2 m, was greater than that in the normal channel. The peak overpressure was also higher than that under normal conditions because of a higher flame speed and stronger pressure piling up. The values of Pmax and Sf increased with an increase in cylinder length. The research results indicate that damage caused by explosions can be reduced by decreasing the gas concentration, which should be immediately detected in roadways with large cross-sections because of the possibility of greater destruction caused by more serious explosions.     

受限空间瓦斯爆炸火焰与毒气传播研究

为揭示瓦斯爆炸过程中火焰、毒气及压力三者间相互关系,采用一端封闭的爆炸试验装置,通过改变瓦斯聚集长度和点火强度,研究了瓦斯爆轰及爆燃状态下火焰、毒气及压力传播变化规律.结果表明,管道内瓦斯爆燃状态下火焰的传播速度远小于爆轰状态下的传播速度,变化趋势呈线性;瓦斯爆炸火焰传播速度的大小直接影响爆轰的形成以及爆炸强度和爆炸传播距离;爆燃状态下火焰和毒气传播的距离基本相当,均为原始瓦斯聚集总长度的2倍左右;爆轰状态下火焰和毒气传播的距离基本相当,均大于原始瓦斯聚集长度,但传播距离不确定.     

瓦斯爆炸过程中火焰厚度的实验室测定及其分析

实验探讨了瓦斯爆炸过程中火焰厚度变化特性及障碍物、膜片位置和压力等的影响。结果表明,障碍物和膜片对瓦斯爆炸过程中火焰厚度具有重要影响。当有障碍物存在时,瓦斯爆炸过程中产生的火焰厚度常常会小于无障碍物存在时所产生的火焰厚度;膜片距离源较近时,火焰厚度明显增大,火焰厚度越大,在其传播过程中对传播途径上的可燃物的点燃作用越大。研究结果对指导现场防治瓦斯爆炸、减轻瓦斯爆炸灾害具有一定的指导意义。     

天津港“8·12”特大火灾爆炸事故建筑物及非结构构件破坏特征

为了研究分析天津港“8·12”特大火灾爆炸事故对建筑物及非结构构件造成的破坏特征,为城市防灾规划中安全距离划定提供依据,在详尽的灾害现场调查及相关数值计算基础上,建议了一种综合描述近场和远场冲击波超压峰值与比例距离关系的表达式。通过与实际建筑物及其玻璃的破坏情况的对比验证,并根据爆炸能量大小和距爆炸源的距离不同,以及可能造成的人员伤亡情况,将灾害危害范围划分为不同的破坏等级,可为城市防灾规划编制提供借鉴。     

起爆位置偏差对结构内爆炸荷载的影响分析

针对结构近距内爆炸试验所得的内爆炸荷载数据离散较大的特点,建立考虑起爆位置偏差影响的三维有限元内爆炸流场计算数值模型,对比试验数据验证了数值计算模型的合理性.采用数值方法计算了起爆位置有偏差时的内爆炸流场,对比分析了起爆位置偏差对结构近距内爆炸荷载的影响.结果表明：结构内爆壁面反射超压峰值对起爆位置偏差非常敏感,拟合得到了起爆位置偏差距离对超压峰值影响系数的经验计算公式;起爆位置偏差对冲量影响很小,其最大相对差值不超过2%.     

爆炸冲击波在钢管混凝土柱表面压力分布试验研究及数值模拟

为了解决爆炸荷载下钢管混凝土柱表面冲击波压力实际分布和数值模拟存在偏差的问题,通过开展钢管混凝土柱爆炸试验,研究冲击波在钢管混凝土柱表面的压力分布,并结合试验建立爆炸荷载下钢管混凝土柱有限元模型,分析不同空气和炸药网格尺寸对冲击波传播及数值分析结果的影响.结果表明:在折合距离为1.1 m/kg1/3试验条件的爆炸荷载作用下,柱顶与柱底的约束条件良好,柱产生的变形属于弹性变形;考察冲击波对构件的损伤程度,应综合考量峰值压力与正压冲量两者的作用效应;不同空气和炸药网格尺寸对爆炸冲击波的压力峰值及压力时程曲线均有较大影响;数值模拟值与试验实测值的误差随着网格尺寸的减小而降低.综合考察数值分析结果与实测值吻合程度,最终确定:空气和炸药网格尺寸为20 mm,符合折合距离不小于1.1 m/kg1/3试验条件下的爆炸数值模拟要求.     

A numerical simulation of the influence initial temperature has on the propagation characteristics of,and safe distance from,a gas explosion

A model roadway with a cross-sectional area of 80 mm × 80 mm and a length of 100 m was used to estimate the overpressure, the temperature, the density, and the combustion rate during an explosion. AutoReaGas software was used for the calculations and the initial temperatures were 248, 268, 308, or 328 K. The methane–air mixture had a fuel concentration of 9.5% and the tunnel had a filling ratio of 10%. The results show that the safe distance necessary to avoid harm from the shock wave increases with increasing initial temperature. The distance where the peak overpressure begins to rise, and where the maximum value occurs, increases as the initial temperature increases. These are almost linear functions of the initial temperature. At locations before shock wave attenuation has occurred increasing the initial temperature linearly increases the maximum temperature at each point following along the tunnel. At the same time, the peak overpressure, the maximum density, and the maximum combustion rate decrease linearly. However, after the shock wave has attenuated the attenuation extent of the peak overpressure decreases with an increase in initial temperature. The influence of the initial temperature on the explosion propagation depends on the combined effects of inhibiting and enhancing factors. The research results can provide a theoretical guidance for gas explosion disaster relief and treatment in underground coal mines.     

Coal Dust Explosions in a Large Scale Experimental Tube

Coal dust explosion conducted in a 200 mm diameter, 29.6 m long tube is prese nted in this paper. 40 dust dispersion system sets were used to disperse coal du st into the tube. A constant temperature hot wire anemometer was used to measure the gas velocity during the dispersion process. Kistler piezoelectric pressure sensors were used to measure the propagation of the pressure wave during the exp losion process. The overpressure of coal dust explosion in the tube was 70 kPa and the velocity of pressure wave...     

障碍物强化爆震起爆和传播的数值模拟与验证

采用非稳态二维轴对称数值模拟的方法研究了圆环形障碍物对爆震起爆和传播的影响,并通过实验进行了验证。研究表明:爆震形成之前,激波的反射与聚交能够产生高温高压点,并大大提高该区域的反应速率,促成局部能量的快速释放,产生局部爆炸;火焰传播速度与相对于障碍物的位置有关,具有极高的脉动特性;DDT(deflagration to detonation transition)过程中迅速增压是在火焰传播到一定区域后开始,在该区域形成向2个方向传播的压缩波,向未燃区传播的压缩波不断加强形成爆震,向已燃区传播的压缩波称为回传爆震,不断衰减;障碍物导致爆震管中压力温度分布极不均匀,与没有障碍物的爆震管完全不同。     

建筑抗爆研究中超压的分布特征及确定方法

爆炸超压是描述爆炸荷载的重要指标,不同方法的超压计算结果具有较高的离散性。通过分析试验数据图表拟合确定入射超压与反射超压关系的反射系数计算式,搜集转化得到大量爆炸超压理论计算公式与爆炸试验数据,从而对爆炸超压在不同比例距离下的分布特征进行分析。研究结果表明：当比例距离小于0.5 m/kg^1/3时,爆炸超压概率密度服从指数分布;当比例距离大于0.5 m/kg^1/3时,爆炸超压概率密度服从正态分布。当比例距离小于0.5 m/kg^1/3时,爆炸超压变异系数达最大值1,比例距离在1.5~6.0 m/kg^1/3之间时,变异系数较小,在0.13~0.2 m/kg^1/3之间;反射超压变异系数较入射超压略大。依据不同比例距离下爆炸超压分布期望数据,拟合得到爆炸超压的计算公式与具有95%保证率条件下的爆炸超压分布范围计算公式。