接触爆炸作用下特大型LNG储罐的动力响应分析

评估特大型(16×104 m3及以上)液化天然气储罐的安全性至关重要,但国内外未见该类储罐抗爆的详细研究,国外现行规范也不能完全满足其安全评估的要求。为此,以某特大型LNG储罐为原型,根据其特有的结构形式,采用流固耦合ALE(Arbitrary Lagrangian Eulerian)算法,对900kg等效TNT炸药在储罐最薄弱处(穹顶中心)爆炸时,爆炸冲击波作用下储罐的动力响应进行了数值模拟分析。由此得到了爆炸冲击波的初始峰值和衰减关系,并通过与经验公式的对比验证了荷载的可靠性;进而得出了接触爆炸作用下储罐结构的破坏情况,以及混凝土、钢筋等的应力分布规律和混凝土单元的位移、加速度响应。结果表明:①等效质量900kg TNT炸药在储罐穹顶顶心处接触爆炸后会在穹顶顶心部位形成一个半径为3m的大变形区;②爆炸对爆心附近25m内的结构影响较大;③900kg TNT炸药等效荷载约为该结构极限承载力。分析结果可为特大型LNG储罐的安全防护对策制定和日常的安全运营提供参考。最后还对储罐的抗爆设计提出了相关建议。

A dynamic response analysis of an extra large LNG storage tank under blasting conditions

It is essential to evaluate the security of an extra large LNG storage tank with the capacity of more than 160 thousand m³, however, such detailed studies have not been found in domestic and foreign literatures, and even the current foreign specifications can not meet the requirements for the security evaluation of such huge tanks under explosions. In view of this, according to the specific structure of a certain extra large LNG storage tank in a case study, the Arbitrary Lagrangian Eulerian and Fluid Structure Interaction were applied to make a numerical simulation of the explosion with a strength of 900 kg TNT equivalence occurring at the dome center, the weakest point of this tank, on this basis, a dynamic response analysis was made of the tank under explosion. As a result, the initial peak and attenuation relationship were obtained of the explosive blast; the reliability of this tank′s load was compared and validated with the empirical formula. Thus, a detailed analysis revealed the law of structure damage and stress distribution of the containment shell under explosion as well as the concrete unit displacement and acceleration response. The following findings were concluded. First, after such an explosion with a strength of 900 kg TNT equivalence, a deformation area with a radius of 3 m formed at the dome center of this tank. Second, the explosion had a rather great impact around the explosion center with a radius of 25 m. And finally, the ultimate bearing capacity of this tank is the strength of 900 kg equivalence. The analysis results can provide references for making safety countermeasures or maintaining routine safe operation of an extra large LNG storage tank. In the end, some proposals were presented for the anti explosion design of LNG storage tanks.