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高地应力条件下隧道或硐室钻爆开挖需考虑初始地应力动态卸荷效应,同时其最终损伤形态会受多个因素影响。采用三维有限差分软件FLAC3D讨论了爆破荷载与地应力动态卸荷复合作用下隧道围岩损伤分布,并重点研究了侧压力系数、岩体力学性质、卸荷速率对围岩损伤范围的影响,最后通过赣龙铁路梅花山隧道开挖损伤区检测结果进行了验证。研究表明,考虑动态卸荷效应的围岩损伤范围明显大于只考虑爆破荷载作用下的围岩损伤范围,在中高地应力条件下,初始地应力动态卸荷对围岩的损伤破坏作用不可忽视;随着侧压力系数逐渐增大,损伤区形态呈现明显的方向性,当侧压力系数为1时,损伤区沿开挖轮廓面分布较为均匀,侧压力系数不为1时,损伤区主要向小主应力方向集中;岩石力学性质越好,损伤范围越小;卸荷速率越快,围岩损伤范围越大,但影响并不十分显著。结果可为高地应力下隧道开挖稳定性分析和支护设计提供一定参考。
Under the condition of high ground stress, the dynamic unloading effect of initial stress should be considered in the tunneling or excavation of tunnels or chambers, and the final damage morphology will be affected by many factors. The threedimensional finite difference software FLAC3D was used to discuss the damage distribution of surrounding rock mass under the combination of blasting load and dynamic unloading of ground stress. The effects of lateral pressure coefficient, mechanical properties of rock mass and unloading rate on the damage range of surrounding rock were discussed. Finally, The test results of the damaged zone of the Meihua Mountain Tunnel in the Ganlong Railway were verified. The research shows that the damage range of surrounding rock considering the dynamic unloading effect is obviously larger than that of the surrounding rock considering only the blasting load. Under the condition of medium - high stress, the damage and destructive effect of the dynamic stress on the surrounding rock can not be neglected. When the lateral pressure coefficient is 1, the distribution of damage zone is more uniform along the excavation profile surface. When the lateral pressure coefficient is not 1, the damage zone is mainly small The main stress direction is concentrated. The better the rock mechanical properties is, the smaller the damage range is. The faster the unloading rate is, the larger the damage range of surrounding rock is, but the impact is not very significant. The results can provide some reference for stability analysis and support design of tunnel under high ground stress.