爆破与瞬态卸荷耦合作用下深埋隧洞围岩损伤演化机制

The transient release of in situ stress on excavation faces, which is caused by rock fragmentation by blasting, is one of the most significant dynamic disturbances during deep rock mass excavation. For a deep-buried tunnel excavation by the full-face millisecond delay blasting technology with considering the effects of the working face advancement, the evolution mechanism of rock damage induced by the coupling action of blasting and transient release of in situ stress will be investigated in this project with a strategy combining theoretical analysis, numerical calculations and field test verification. By modelling the process of rock crack initiation and propagation during the deep-buried tunnel excavation by blasting, a 3D model is expected to be developed for the coupling of blasting and transient release of in situ stress. According to this model, the space-time distribution of the coupled stress field will be studied, including the static in situ stress and the stress waves induced by the coupling action of blasting and transient release of in situ stress. Furthermore, the mechanism and 3D evolution process of rock damage will also be studied with a special emphasis on the repeated disturbances of the coupling action. On the basis of the above work, it is expected to reveal the time-domain evolution history of damage and its spatial distribution characteristics in surrounding rock masses for the deep-buried tunnel excavation by the full-face millisecond delay blasting sequence, and propose blasting damage thresholds for the deep–buried tunnel excavation with considering the effects of the repeated excavation disturbances. The research results can provide a theoretical basis for the failure and deformation control of surrounding rock masses during the deep underground opening excavation, and find widespread application in the industries of hydropower, transportation, deep mining and deep geological disposal of radioactive waste.

爆破导致的开挖面上地应力瞬态释放是深部岩体开挖扰动的主要因素之一。本项目针对深埋隧洞毫秒延迟爆破全断面开挖和开挖掌子面循环推进过程，拟采用理论分析、数值计算和现场试验验证相结合的方法，研究爆破与瞬态卸荷耦合作用下的围岩损伤演化机制。通过深埋隧洞钻爆开挖岩体开裂破碎过程模拟，建立爆破与岩体开挖瞬态卸荷耦合作用的三维力学模型；分析深埋隧洞爆破开挖过程中围岩动静组合应力场的时空变化规律，研究爆破与瞬态卸荷反复作用下的围岩损伤机理与演化过程，揭示深埋隧洞钻爆开挖围岩损伤时域内的演化历程和空间分布特征，提出反映爆破与瞬态卸荷耦合作用反复扰动影响的深埋隧洞开挖爆破损伤安全阈值。研究成果可为深埋隧洞开挖围岩损伤和变形控制提供理论依据，在水电、交通、深部采矿和核废料深埋处置等工程领域具有广阔的应用前景。

项目以西南高山峡谷地区大型水电工程建设为背景，针对深埋隧洞毫秒延迟爆破全断面开挖和开挖掌子面循环推进过程，研究了深部高地应力岩体爆破破碎过程，确定了爆破开挖面上地应力瞬态卸荷力学过程，建立了爆破与岩体开挖瞬态卸荷耦合作用力学模型；通过研究爆破与岩体开挖瞬态卸荷耦合作用反复扰动引起的围岩应力场调整和围岩损伤演化过程，探明了深埋隧洞爆破开挖诱发围岩损伤破坏的动力扰动机制，揭示了深埋隧洞爆破开挖围岩损伤时域内的演化历程和空间分布特征，提出了反映爆破开挖扰动反复作用影响的深埋隧洞开挖爆破损伤安全阈值。结合项目研究，发表论文16篇，其中SCI论文6篇、EI论文6篇，出版专著1部，培养硕士研究生4人。项目成果有助于加深对深部岩体工程开挖扰动区形成机理与演化规律的认识，丰富了深部岩体开挖效应的分析理论与计算方法，在水利水电、深部采矿和核废料深埋处置等深部岩体工程领域具有推广应用前景。