城市燃气管道泄漏爆炸事故三维风险数值模拟

On a 3-D risk numerical simulation for the leakage explosion accident of the urban gas pipeline

城市燃气管道在发生泄漏导致火灾爆炸事故时,在空间某点形成的风险,不仅与泄漏量、泄漏时间有关,还与空间有无障碍物、泄漏环境等因素有关。基于物理场经典的场理论,定义城市燃气管道泄漏爆炸事故的风险场,推导出多个危险源在空间某点形成的风险强度公式。利用ANSYS/LS-DYNA数值模拟软件模拟有无障碍物时爆炸事故形成的风险在空间传播规律。结果表明,障碍物对空气超压峰值的影响具有距离效应。在障碍物近区,空气冲击波经反射叠加作用造成超压峰值急剧升高;在障碍物远区,空气冲击波经障碍物反射后由于随距离衰减过快,对超压峰值影响微弱,甚至没有影响。同时对有障碍物存在时进行爆炸破坏效应模拟,得到爆炸破坏效应的5个分区,界定了爆炸破坏对人身伤害程度范围。首次提出了城市燃气管道泄漏爆炸事故风险场的概念,并运用风险场理论研究了空间某点多个危险源同时存在时的风险传播问题。

This paper takes it as the target to study the leakage explosion accidents of the urban-area gas pipeline system based on a 3-D risk numerical simulation based on the application of the classic physics field theory. For the said study purpose,we have first of all to identify and define the risk field of the urban gas pipeline system leaking explosion accidents. According to the vector synthesis rule of the engineering mathematics,risks likely to be caused by such danger-involving resources can be regarded as a space vector,whereas the risk intensity formula can be gained in accordance with the multiple danger-causing resource depending on the certain risk point in space. Since the propagation of the explosion accident risk is prone to be affected by the wind speed and other environment factors,the environmental correction coefficient K should take into account the influential factors favorable for the theoretical deduction of the likely accidents in line with the actual situation. Therefore,we think it necessary to simulate the authentic building（ structure） as an obstacle to provide evidence of the obstacles with a clear effect on the risk of the urban gas pipeline leakage explosion accident,via a numerical simulation software known as ANSYS / LS-DYNA. According to the symmetry 1 /2 of the above 3-D gas explosion model analysis under the condition with and without the obstacle,the blast area size should be equal to 11 m × 3 m × 3 m,whereas the gas explosion source has to be equal to 5 kg TNT. And both of the distance between the explosion source and the ground-surface should be 0. 5 m,with the distance between the obstacle and explosion source being 10 m when there exists any obstacle. The above research result can be used to simulate the transportation regularity of the risk by the explosion accident. Hence,the simulation results can help to disclose that the impact of the obstacles on the peak value of the air overpressure may also influence the distance. In addition,around the obstacle area,the peak value of the overpressure may increase more quickly due to the reflection to and the superposition of the air shock waves. Nevertheless,with the increase of the distance,the shock waves in the air tend to decrease quickly when they are reflected by the obstacle. Therefore,it is likely that the effect may be getting weaker and weaker till no effect will be made on the overpressure result. At the same time,this paper has also simulated the explosion damage effect whenever there exist the obstacles,so as to gain the explosion damage effect of the five fields. Thus,it can be seen that the paper has first of all provided the risk field concept of the urban gas pipeline system leakage explosion,then,we have also explored the risk transferring regularity in case there may simultaneously exist multiple hazard points according to the risk field theory.