液化天然气储罐混凝土穹顶的冲击破坏模式与机理

Damage modes and failure mechanism of concrete dome of LNG storage tank

为获得大型全容式LNG储罐混凝土穹顶结构在圆柱形刚体冲击作用下的动力响应、失效模式以及失效机理,基于160 000 m^3的LNG储罐,应用ANSYS/LS-DYNA建立LNG储罐精细化有限元数值模型,并通过对弹丸冲击混凝土靶板实验的数值模拟,验证了有限元模拟方法及材料模型的适用性。通过分析圆柱体冲击物撞击下LNG储罐的动力响应,提出储罐穹顶结构的3种失效模式即局部凹陷、混凝土剥落、击穿破坏,并根据冲击过程中能量的传递特征揭示了每类失效模式对应的失效机理。最后通过大量参数分析获得不同冲击物直径、冲击位置、冲击角度对LNG储罐结构的最大冲击响应及失效模式的影响规律。结果表明,冲击角度、冲击物直径对LNG储罐混凝土外罐穹顶的失效模式影响较大,冲击位置对储罐穹顶失效模式的影响较小,可以忽略。

In order to investigate the damage modes and failure mechanism of the concrete dome of the liquefied natural gas(LNG)storage tank subjected to impact by a rigid circular cylinder,the finite element(FE)model of the outer concrete tank of the 160 000 m 3 LNG storage tank for an actual LNG project and a cylindrical impactor is established based on ANSYS/LS-DYNAFE analysis software platform.The accuracy of the numerical simulation method and the material model employed has been verified by simulating the impact perforation of reinforced concrete slabs subjected to projectile with high speed.The dynamic response of structures under impacting with variable speed,angle,location,and diameter are studied.Based on the dynamic response of the outer concrete tank of the LNG storage tank subjected to impact loading,three damage modes are defined and the failure mechanism of each mode is revealed from the point view of energy.The response characteristics and rules with the change of the impact parameters are obtained.The results show that the impact angle and the diameter of the impactor affect significantly on the failure modes of dome,and the impact position at the dome has a negligible effect on the failure modes.