基于数值模拟的多跨简支梁桥拆除爆破技术

Demolition blasting technology of multi span simply supported beam bridge based on numerical simulation

为了保证紧邻运营新桥的多跨简支梁旧桥顺利倒塌,针对待拆桥梁的结构特点与周边环境,在桥梁拆除前进行了定量化的爆破设计。采用大型有限元显示动力学软件AUTODYN对待拆桥梁的主要承重结构墩柱进行了爆炸模拟,模拟了墩柱在爆炸荷载下的动态响应。根据数值模拟结果确定了墩柱炮孔的孔深、孔距、单耗及单孔装药量等爆破参数;采用ANSYS/LS-DYNA模拟桥梁不同倒塌方式下的倒塌过程,对比分析了不同方案下桥梁的倒塌方向、分段延时及桥体塌落范围。结果表明:采用侧向延时起爆桥体倒塌方向、倒塌范围得到有效控制。利用数值模拟技术对待拆旧桥的爆破参数进行了一系列的验证与优化,并成功运用到实际工程中,该技术路线可以为类似的工程实践提供参考。

In order to ensure the smooth collapse of the old multi span bridge with simply supported beams,which is adjacent to the operating new bridge,quantitative blasting design was carried out based on the structural characteristics and surrounding environment of the old bridge before the demolition.The large-scale finite element display dynamics software AUTODYN was used to simulate the explosion of the main bearing structure of the old bridge,and the dynamic response of the pier under the explosion load was simulated.The blasting parameters such as hole depth,hole distance,powder factor and single hole charge are determined by numerical simulation results.The collapse processes of bridge under different collapse schemes are simulated by ANSYS/LS-DYNA,and the collapse direction,section delay and collapse scope of bridge are compared and analyzed.The results show that the collapse direction and collapse scope of bridge can be effectively controlled by using lateral delay initiation.A series of verification and optimization of blasting parameters of the old bridge are carried out by using numerical simulation and the parameters are successfully applied to the project,which could provide reference for similar engineering practices.