储罐爆炸抛射碎片对目标储罐的破坏概率研究

化工储罐爆炸产生的抛射碎片击中并破坏相邻罐体后,将引发多米诺效应。N guyen破坏概率模型认为,当罐壳受撞击后,残余壁厚小于某个临界值时就会被破坏,并假设该临界残余壁厚为定值,存在不合理之处。本文基于储罐壳体损失面积安全评价方法AP I 579,把撞击形成的复杂凹坑简化为圆锥形,分别针对圆柱储罐、球罐推导出圆锥形凹坑剩余强度系数的求解方法,并根据塑性失效理论确定了罐壳的临界剩余强度系数,由此建立了新的破坏准则。在此基础上,采用蒙特卡罗法进行模拟,建立了新的爆炸碎片对目标储罐的破坏概率模型,与N guyen模型相比,得出的破坏概率偏大,结果更为安全保守。通过对剩余强度系数与无量纲撞击深度和凹坑锥角的变化关系进行分析,证明N guyen模型中临界残余壁厚为定值的假设并不合理,而新的基于剩余强度系数计算的破坏概率更为准确合理。

Damage Probability Model of Target Storage Tank Impacted by Explosion Fragments

The fragments generated from exploded chemical storage tank would cause the domino effect after impacting on other neighboring equipments.In Nguyen′s damage probability model,a constant critical residual thickness of tank shell is assumed and taken as a criterion.However,the value of the thickness is unreasonable and difficult to be determined.Based on the API 579 method for safety assessment of lost area of the vessels shell,a new damage probability model was presented.At first,the complex pits formed by the impact were simplified as conical pits.Then,the calculation equations of residual strength coefficients were derived and critical residual strength coefficient was determined based on the plastic failure theory.Finally,a new damage probability model was established with Monte Carlo method.Comparison results of the two models show that the prediction probabilities of the new model are larger than that of the Nguyen′s model.It is also found that damage probabilities increase with the perforation and are influenced by the cone angle of the conical pit.So it can be proved that the hypothesis of Nguyen′s model,that the critical residual thickness was a constant,is unreasonable.