顶爆和拱腰侧爆同时作用下锚固洞室的动态响应

基于相似模型试验,采用显式非线性动力分析程序LS-DYNA3D研究了地下锚固洞室在拱顶和拱腰侧两处集中装药爆源同时爆炸作用下应力波传播规律、裂纹形成机理以及洞壁围岩位移分布特征。通过对比分析顶爆试验和计算模型的压应力时程曲线,发现模拟与试验结果吻合,且符合应力波的传播规律,表明数值模拟结果可靠。爆源爆炸后,应力波以圆形向周围岩体传播,两应力波相遇处压应力强度明显大于周围岩体;当应力波传到自由面时,会反射形成拉伸波,在地表下方和洞室上方发生“层裂”现象,在拱顶和拱腰侧爆源中间沿洞室径向有裂纹延伸,由于拉伸波的叠加,在爆源下方出现“八”字形的锥形裂纹面。锚杆能够起到加固岩体的作用,锚固洞室比毛洞裂纹分布少,毛洞迎爆侧裂纹主要为横向裂纹,而锚固洞室则为径向劈裂和横向裂纹。两爆源中点洞室径向处的洞壁围岩位移峰值最大,极易产生破坏。

Dynamic Response of Anchorage Chamber under Simultaneous Explosion Load from Top and Side of Arch

Based on the similar model test,the stress wave propagation rule,crack formation mechanism and displacement distribution characteristics of rock mass in the underground anchorage chamber under the simultaneous explosion of concentrated explosive source at top and side of arch are studied by explicit nonlinear dynamic analysis program LS-DYNA3D.By comparing and analyzing the compressive stress time-history curves of the experimental and calculation model,it is found that the simulation results are consistent with the experimental results and conform to the stress wave propagation law,which indicates that the numerical simulation results are reliable.Under explosion of the source,the stress wave propagates to the surrounding rock mass in a circular way.When the stress wave is transmitted to the free surface,it will be reflected and form the stretching wave,which forms the phenomenon of“spalling crack”under the ground and above the tunnel.There are cracks extending along the radial direction of the chamber at the middle point of the explosion source on the top and side of arch.The bolt can play a role in strengthening the rock mass.The distribution of cracks in the anchorage chamber is less than that in the unanchored chamber.The displacement peak value of the surrounding rock at the radial axes of the two blasting sources is the largest and most easily destroyed.