瞬态卸荷效应下岩爆损伤度判别

Judgement of Rock Burst Damage Degree under Transient Unloading

在地下硐室爆破开挖过程中,初始地应力的卸载是一个高速动态卸载过程,该瞬态卸载在掌子面附近的岩体中激起动态卸载应力波并造成围岩损伤。针对围岩瞬态卸荷过程对爆破破岩的作用及瞬态卸荷动力学效应,开展围岩动力响应计算和岩体瞬态卸荷全过程模拟,通过识别损伤范围和分析岩爆强度衡量值以判别围岩的危险性。结果显示,高地应力条件下开挖荷载的瞬态卸荷动力学效应是显著的,径向应力的卸载和切向应力的加载,与相同条件下的机械掘进TBM相比,其诱发岩爆的可能性大大增加。所以,在较强岩爆倾向性的岩体中进行爆破开挖时,要更加注意爆破过程造成的原始应力突然释放所诱发的岩爆灾害,通过调整施工进度或调整施工步骤,可以有效降低岩爆发生的概率和强度。

During the excavation of underground chambers, the unloading of initial ground stress was a high-speed dynamic process. The transient unloading in the rock mass near the surface induced dynamic unloading stress waves and caused the dam- age of the surrounding rock. Aimed at the effect of rock transient unloading process on rock burst and transient unloading dy- namics, the dynamic response calculation of surrounding rock was carried out, and the whole process of rock mass transient unloading was simulated. By identifying the damage range and analyzing the value of rock burst strength, the hazard of sur- rounding rock was judged. The results showed that the dynamic effect of transient unloading under the high stress was signifi- cant, which showed the unloading of radial stress and the loading of tangential stress. Compared with the TBM tunnelling un- der the same conditions, the possibility of induced rock burst was greatly increased. Therefore, when blasting excavation was carried out on rock mass with strong rock burst prone, more attention should be paid to the rock burst hazard caused by sudden release of original stress in the blasting process. By adjusting the construction progress or steps, the probability and intensity of rock burst could be effectively reduced.