爆炸荷载下锚固洞室拱脚的变形破坏规律研究

Deformation and failure of the arch springing of anchored tunnels subjected to explosive loads

在爆炸荷载的作用下,洞室拱脚部位常产生较大的变形而破坏。通过模型试验,研究了集中装药条件下,6个不同锚杆加固方式的洞室拱脚处的变形破坏规律。对选取的典型洞室洞壁的6个不同部位测点的应变波形、峰值及其残余值大小进行了探讨;重点比较分析了各个洞室之间拱脚部位两个测点应变波形特征及其变化规律。结果表明:洞室拱顶部位一般产生拉应变,其他部位产生压应变;拱脚两测点应变峰值和残余值比其它部位测点的大;当锚杆长度不变时,锚杆间距变化规律与拱脚拱部的变形规律具有一致性;当锚杆间距不变时,锚杆长度变化规律与拱脚直墙部位的变形规律具有相反性;长密锚杆加固使洞室围岩形成了范围更大的“加固拱”结构,故其拱脚的抗变形能力更强。

The arch springing of tunnels might fail due to the great deformation generated when it is subjected to explosive loads.Through model tests,the deformation and destroying of the arch springings of six tunnels with different rock bolts’ reinforcement patterns under concentrated charge were investigated.The strain waveform,peak and residual values at six different positions in one selected typical tunnel were compared and analyzed.Then,the characteristics of strain waveform at two focused measuring points on the arch springing and their variations were emphatically discussed for each tunnel.The results show that tensile strain occurs generally at the arch vault,and compressive strain occurs at other measuring points.The strain peak and residual values at two measuring points on the arch springing are larger than those at other points.When the length of the rock bolts keeps constant,the deformation of the arch part of arch springing varies in consistency with the change of rook bolts’ spacing.When the spacing of the rock bolts keeps constant,the deformation of the straight wall of arch springing varies in opposite to the change of the rock bolts’ length.The reinforcement effect of long and dense rock bolts makes the surrounding tunnel rock form a reinforced arch structure,and this will improve the anti-deformation ability of arch springing.