构造破碎带隧道掌子面稳定性及加固效果分析

在构造破碎带地层中隧道开挖掌子面易失稳。采用有限元软件MIDAS/GTS模拟上下台阶法开挖,研究掌子面失稳机理及需采取的应对措施,并提出8种掌子面加固方案。结合洞内掌子面与拱顶监测数据,研究各加固方案下掌子面挤出位移、拱顶沉降位移及掌子面塑性应变。研究结果表明:构造破碎带掌子面挤出位移过大,地层软弱易进入塑性状态致使掌子面失稳;上台阶掌子面的中下侧为最容易失稳部位;采用原始支护+注浆加固4 m的方案对掌子面注浆加固能降低掌子面挤出位移、拱顶沉降位移及塑性应变,该方案支护效果最佳。

Stability and Reinforcement Effect of Tunnel Face in Tectonic Fractured Zone

The tunnel face excavation in the stratum of tectonic fractured zone is liable to be unstable.The f inite element software MIDAS/GTS was used to simulate the excavation of upper and lower bench method,the instability mechanism of the tunnel face and the measures to be taken were studied,and eight reinforcement schemes of the tunnel face were put forward.Combined with the monitoring data of tunnel face and vault in the tunnel,the extrusion displacement of tunnel face,settlement displacement of vault and plastic strain of tunnel face under various reinforcement schemes were studied.The research results show that the extrusion displacement of the tunnel face in the tectonic fracture zone is too large,and the stratum is weak and easy to enter the plastic state,which results in the instability of the tunnel face. The middle and lower sides of the upper bench tunnel face are the most vulnerable to instability,the tunnel face reinforcement scheme of original support and grouting reinforcement with 4 m can reduce the extrusion displacement,vault settlement displacement and plastic strain of the tunnel face,and the support effect of this scheme is the best.