节段拼装桥墩在爆炸冲击作用下的破坏模式与损伤评估研究

Failure mode and damage assessment of segmental assembled pier under blast Impact

为研究爆炸冲击作用下节段拼装桥墩的破坏模式和损伤评估方法,采用ANSYS/LS-DYNA建立方形截面整体式桥墩和节段拼装桥墩受爆的三维实体分离式模型。基于与爆炸试验结果的对比分析,验证该模拟方法的可靠性。通过改变爆炸TNT当量和爆炸距离,对比分析了不同超压作用下整体式桥墩与节段拼装桥墩的应力变化、破坏模式与损伤机理,并提出结合截面损伤与墩身侧移的桥墩受爆损伤评估方法。结果表明:在爆炸冲击与恒载共同作用下,整体式桥墩主要呈现剪切破坏与弯剪破坏,节段拼装桥墩主要呈现剪切破坏与局部破坏;在不同比例距离的爆炸冲击作用下,桥墩的损伤均可分为完全弹性、部分弹性及失去弹性等三种状态;节段拼装桥墩在受到爆炸冲击作用后,墩身节段间产生较大相对转角和位移,进而导致节段截面削弱和墩身侧移;两种体系桥墩均可采用截面削弱与墩身侧移相结合的方法,进行爆炸损伤的定量评估。

In order to investigate failure mode and damage assessment method for segmental assembled piers under blast impact,3-D solid separated models of integral pier with square section and segmental assembled pier under blast were established using the software ANSYS/LS-DYNA.The reliability of this simulation method was verified by comparing the numerical results and the blast test ones.By changing the blast’s TNT equivalent and blast distance,the stress variation,failure mode and damage mechanism of integral pier and segmental assembled one under different overpressure actions were contrastively analyzed,and the method for evaluating pier blast damage combined with pier section damage and its lateral displacement was proposed.Results showed that under combined action of blast impact and dead load,integral piers mainly exhibit shear failure and bending-shear failure,while segmental assembled piers present shear failure and local failure;under action of blast impact with different scaled distances,pier damage can be divided into 3 states of complete elasticity,partial elasticity and loss of elasticity;after segmental assembled piers are subjected to blast impact,larger relative rotating angle and displacement occur between segments to cause weakening of pier section and pier body lateral displacement;blast damage for both bridge piers of the two systems can be quantitatively evaluated with the combination method of section weakening and pier body lateral displacement.