隧道围岩爆破冲击损伤防护的轻气炮试验及数值模拟

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57mm口径的一级轻气炮装置和LS-DYNA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4mm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。

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

Based on the traditional charge stucture of smooth blasting, a new stucture that packed PVC-U material beside blasthole is proposed for protecting tunnel surrounding rock.The working theory of the material in reducing the impact damage toward tunnel surrounding rock is also investigated. For verificating the effect of PVC-U material in decreasing surrounding rock’s damage, the Ф57mm one-stage light-gas gun is used to carried out experiments with the LS-DYNA analysised software dissecting tests’ data. Test’s result indicates that with this protective layer could diminish the stress peak and damage of rock sample’blasting surface. And with same condition of impact velocity,the thicker of the PVC-U material layer, the lower of the blasting surface stress peak value. By using 4mm protective layer,the injury tolerance of rock test specimen reduced 21.1%.Moreover ,the validity of theoretical analysis and test result are also checked by numerical simulation method.And the conclution is that PVC-U material layer in the blast hole can reduce the blasting damage of tunnel surrounding rock.