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三联隧道煤系地层段围岩软弱,地应力高,初期支护变形速率快,累计变形量大。初支封闭成环后变形仍持续发展,大变形问题突出。运用FLAC2D有限差分软件对隧道施工情况进行二维模拟,数值模拟结果及现场情况分析表明,地质复杂、围岩软弱、高地应力、初支刚度不足等是导致大变形的原因。根据弱支护和强支护两种工况数值模拟结果对比,提出了采用强支护控制大变形;同时加强辅助施工措施、及时施作仰拱和尽量紧跟加强型二衬。采用上述措施后,位移量测结果表明大变形控制效果良好,二衬应力测试结果表明衬砌结构安全。因此,上述大变形控制措施切实可行。
The surrounding rock of the coal tunnels in the triple tunnel is weak and has high ground stress. The deformation rate of the initial support is high and the accumulated deformation is large. After the initial branch closed loop deformation continues to develop, highlighting the major deformation. The finite element software FLAC2D is used to simulate the tunnel construction situation. The numerical simulation results and field analysis show that the complex deformation, the weak surrounding rock, the high ground stress and the insufficient primary stiffness are the reasons for the large deformation. According to the comparison between the numerical simulation results of weak support and strong support, the paper puts forward that using strong support to control the large deformation, strengthening the auxiliary construction measures, applying the inverted arch in time and trying to follow the reinforced second lining. After adopting the above measures, the results of displacement measurement show that the effect of large deformation control is good, and the result of the second lining stress test shows that the lining structure is safe. Therefore, the above-mentioned large deformation control measures are feasible.