高地应力环境下硐室开挖围岩应力释放规律

The wall-rock's stress releasing regularity arose by cavern excavation in the high stress condition

为研究高地应力环境下硐室掘进引起的围岩应力时空变化规律,以某地下工程模拟试验硐为例,开展了原地应力测量,应用压磁电感法高精度应力测试系统对地下硐室挖掘过程中围岩应力变化的全过程进行了跟踪监测。结果表明:高应力区试验硐掘进引起的围岩应力变化有应力释放、应力调整和应力平稳3个阶段;垂直于硐壁方向的应力变化最显著,距离硐壁0.6 m处原地应力基本完全释放;平行于硐壁方向的应力变化较小,释放掉原值的20%,应力在放炮时瞬间释放完毕;观测到最小主应力在调整阶段有2 MPa左右的应力加强现象。

In order to research the spatial and temporal changing regularity of wall-rock＇ s stress arose by cavern excavation in the high stress condition, took the site and experimentation of one underground engineering as an example, did the measurement of insitu stress, and used the piezomagnetic induction high-precision stress measuring system to tracking monitor the entire changing process of wall-rock＇ stress during the excavating process in the cavern. The result shows that there are three stage of wall-rock＇ s stress change in the excavating process, that are stress releasing stage, stress adjusting stage and stress stabilizing stage. The change of stress is the most significant in the direction of against the cavern wall, and the in-situ stress is almost wholly released at a distance of 0. 6 m from the cavem wall. Stress change along the cavern wall is slighter, and only 20% of the original value is released. The stress releasing process is completed in the instant of shot. The observation shows that the minimum principal stress has a stress enhancing phe- nomenon at a magnitude of about 2 MPa during the stress adjusting stage.