基于ANSYS/LS-DYNA的竖井掏槽延时爆破研究

Research on delay blasting of shaft cutting based on ANSYS/LS-DYNA

为了探究小间距地下在建构筑物爆破施工对既有地下结构的影响,以米仓山竖井及隧道工程为例,从竖井掏槽孔延时爆破的角度,采用有限元软件ANSYS/LS-DYNA,针对既有隧道的降振效果进行了一系列的数值模拟。模拟结果表明:当多个掏槽孔同时起爆时,爆破地震波的传播易受传播介质及传播距离的影响,且爆破地震波具有明显的主振段;延时爆破可实现多个爆破波不同程度的叠加消能情况;当延时时间为2 ms,即为主振周期的一半时,既有隧道降振效果十分显著;延时时间大于主振周期时,降振效果同样明显,但主振区持时也相应拉长,可能会为隧道带来长持时的塑性破坏;此外,竖井掏槽时间的确定应结合结构的破岩效果进行考虑。

In order to explore the impact of blasting for new underground structures in a small spacing to existing underground structures,a series of numerical simulations of millisecond delay blasting in cut holes of the Micangshan shafts and tunnels for the study of vibration reduction effect of existing tunnels were carried out by using the finite element software ANSYS/LS-DYNA.The results show that the propagation of blasting seismic wave is easily affected by the propagation medium and the propagation distance when multiple cut holes are fired simultaneously,and the blasting seismic wave has an obvious main vibration segment.The superposition energy dissipation of multiple blasting waves can be realized by millisecond blasting.When the delay time is 2 ms,that is,half of the main vibration period,the vibration reduction effect of the existing tunnel is very significant.When the delay time is larger than the main vibration period,the vibration reduction effect is also obvious,but the main vibration area is stretched,which may bring the plastic failure to the tunnel at a long duration.In addition,the determination of delay time should be considered in combination with the rock-breaking effect of the structure.