地下洞室开挖过程围岩应变能调整力学机制

深埋洞室岩体开挖过程中，围岩应变能的聚集和释放是洞室发生灾变破坏的重要诱因。针对圆形洞室开挖，分析和比较初始地应力准静态和动态两种不同卸载方式下围岩应变能的调整过程，基于能量角度判定了围岩损伤范围。研究表明：伴随地下洞室的开挖，岩体能量靠径向应力做功的方式在围岩中由远及近传递，并导致近区围岩应变能聚集；初始地应力动态卸载诱发围岩应变能先减小后增大，先对靠近开挖面的相邻岩体通过径向应力做功的方式释放自身的应变能，随着卸载应力波的继续向前传播，远离开挖面的相邻岩体又通过径向应力对其做功的方式促使其应变能聚集；相比初始地应力准静态卸载，动态卸载条件下高应变能聚集程度导致围岩损伤破坏范围更大。

Mechanism of strain energy adjustment of surrounding rock during excavation of underground caverns

During the excavation of deep caverns, the strain energy accumulation and release of surrounding rock are the most important incentives to cause the catastrophe damage. Aiming at the excavation of circular tunnel, the energy transient adjustment process of surrounding rock under the different unloading ways of initial in-situ stress (static and dynamic unloading) is analysed and compared, and based on energy point of view the damage scale of surrounding rock is calculated. The results show that, energy transmits from far and near in the surrounding rock by the radial stress working under the unloading of initial in-situ stress, and causes the strain energy of the near parts of surrounding rock gathering, with the excavation of underground caverns and tunnels. The strain energy of the near parts of surrounding rock decreases firstly and then increases, this caused by the dynamic unloading of initial in-situ stress; firstly the rock releases its own strain energy by radial stress working on the adjacent rock mass near the excavation surface, with the continuous transmission of the unloading stress wave, its own strain energy gathers by the working of adjacent rock mass away from the excavation surface. Comparing with the static unloading of initial in-situ stress, the high strain energy accumulation degree caused by the dynamic unloading of initial in-situ stress leads the larger extent of damage zone.