基于尺寸效应的节理岩体隧道开挖稳定性分析

节理岩体的开挖力学响应具有显著的尺寸效应，这对于研究隧道稳定性非常重要。运用离散单元法，模拟了相同隧道尺度条件下不同节理间距的4组情况。研究结果表明:①随着岩体节理间距减小，围岩结构类型由整体块状逐步转化为碎裂状，随之出现岩块松动脱落；②围岩塑性区、应力松动区以及节理张开区具有相似的分布规律，均随着节理间距减小而增大，但发生岩块松动脱落之前的尺寸效应不明显；③节理剪切滑移破坏区比张开区和岩体塑性区更大，且具有更加明显的尺寸效应，适合作为节理岩体隧道稳定性的判别指标。

Analysis on Tunnel Excavation Stability in Jointed Rock Mass Based on the Size Effect

The mechanical response of jointed rock mass excavation is of significant size effect, which is very important for studying the stability of tunnel. There are four cases with different joint spaces and same tunnel size studied by the discrete element method(DEM). The study shows that:①the structure type of surrounding rock mass transfers from blocked state to fractured one with the decrease of joint space, while the loosing and falling of rock take place. ② The plastic zone, stress loosen zone of surrounding rock mass and the open zone of joint have similar distribution rules of each other, which will increase with the decrease of joint space and appear little evident size effect before the loosing and falling of rock. ③ The shear slip failure zone of joint is bigger and has more evident size effect than the open zone of joint and plastic zone of surrounding rock mass, thereby it is suitable for the stability criterion of jointed rock mass tunnel.