隧道围岩爆破冲击损伤防护的轻气炮试验及数值模拟

Tests and numerical simulation for impact damage protection of tunnel surrounding rock

为减小爆破对隧道围岩的损伤破坏,在传统光面爆破装药结构基础上,设计了一种在炮孔一侧安放PVC-U材料来保护隧道围岩的装药结构,并分析了该装药结构在爆破过程中对隧道围岩损伤防护的机理。为进一步验证PVC-U管的防护效果,利用57 mm口径的一级轻气炮装置和LS-DYNA 3D软件进行了岩石冲击损伤破坏分析。结果表明:保护层能够降低岩石试件冲击面上的应力波峰值和减小试件的损伤程度;在相同冲击速度下,岩石试件冲击面上的应力波峰值随保护层厚度的增加而不断下降。加有厚4 mm保护层材料的岩石试件的损伤度较无保护层时降低了21.1%。对岩石试件的冲击过程进行的数值模拟验证了理论分析和试验结果的正确性。说明放置在炮孔内的PVC-U管能够对岩石的爆破损伤破坏起到一定的防护作用。

Based on traditional charge stucture of smooth blasting,a new stucture that packed PVC-U material beside blasthole was proposed for protecting tunnel surrounding rock.The working mechanism of the material to reduce impact damage toward tunnel surrounding rock was also investigated.For verifying the effect of PVC-U material to decrease surrounding rock＇s damage,the Ф57mm one-stage light-gas gun was used to perform experiments and the LS-DYNA software was used to analyze tests＇ data.Test＇s result indicated that with this protective layer can drop the stress peak and damage of rock sample＇blasting surface;and with the same condition of impact velocity,the thicker the PVC-U material layer,the lower the blasting surface stress peak value;by using 4mm protective layer,the injury tolerance of rock test specimen reduces 21.1%;moreover,the validity of the theoretical analysis and the test results are checked by numerical simulation method;so,PVC-U material layer beside blast hole can reduce blasting damage of tunnel surrounding rock.