节理岩体中隧洞围岩的损伤破坏机理

Damage and Failure Mechanism of Tunnels in Jointed Rock Mass

结合细观节理形态的变化,在二轴围压条件下,数值模拟了节理岩体中隧洞围岩损伤破坏过程,研究了节理岩体中隧洞围岩体的破坏机理,分析了岩体中节理倾角对隧洞围岩稳定性的影响规律.结果表明:裂隙的产生和发展延伸主要是拉应力的作用,裂隙延伸方向大致与节理面垂直;节理倾角较小时,岩体中破裂以垂直于节理面的拉裂隙为主;节理倾角较大时,岩体裂隙以沿节理面的滑动裂隙为主;不同倾角的节理面对岩体破坏的脆性也有较大影响;岩体破坏前有大量微裂隙产生,同时伴随着声发射能量的释放,利用微震监测技术抓住这些微破裂前兆信息,能够较好地进行隧洞塌方、冒顶、岩爆等灾害预测,提前做好支护等应对措施,以保障人员、设备安全.

In consideration of the the variation of mesoscopic pattems of joints, the damage process of surrounding rock of an underground opening in jointed rock mass was numerically simulated, and the failure mechanism of surrounding rock was investigated. The effect of the dip angles of joints on the stability of surrounding rock was examined. The results showed that the tensile stress causes mainly the initiation and propagation of the cracks, and the propagation direction of the cracks is roughly normal to the joint surface. The tensile cracks normal to the joint surface are the dominant fracture behaviors around the opening in the rock model with a low joint dip angle, while, the joint sliding are the dominant in the model with a high joint dip angle. The dip angle of joint surfaces also affects the fragility of rock mass. With the initiation of micro- fracture before the rock failure, a lot of energy will be released as acoustic emission. By using micro-seismic monitoring technology to get the information of energy release, the collapses, roof falling, rock burst and other disasters can be possibly forecasted, thus the supporting measures could be taken in advance to keep staff and equipment safe.