蒙华铁路中条山隧道高地应力F7断层软岩破碎段施工技术

Construction Technology for Soft Rock Fracture Section of F7 Fault of Zhongtiaoshan Tunnel on Menghua Railway under High Ground Stress

为解决中条山隧道在施工至高地应力F7主干断层段时,左右线已施工完成的247 m初期支护发生严重变形开裂的问题,选取不同段落对"刚性支护一次到位"和"柔性支护释放应力后进行二次支护"2种方案进行试验,通过对监控量测数据分析和初期支护表面观察,得出以下结果:1)软岩大变形段落采取"刚性支护一次到位"相比"柔性支护释放应力后进行二次支护"变形速率明显下降,最大收敛速率由28 mm/d下降至18 mm/d,最大沉降速率由24 mm/d下降至12.8 mm/d,释放应力时发生变形的"度"更易掌控;2)在采取"刚性支护一次到位"的基础上,辅以优化"隧道边墙曲率"和"施工工法"等措施,能够有效控制隧道初期支护变形开裂,确保隧道结构的质量,顺利通过F7主干断层。

In order to solve the serious deformation crack of primacy support （247 m of excavated section ） of Zhongtiaoshan Tunnel when encountering F7 main fault with high ground stress, two schemes, i.e. one time rigid support and stress release by flexible and secondary support, are carried out for different test sections; and then the monitoring data are analyzed and the primary support appearance is observed. Some conclusions are drawn as follows： （ 1 ） The deformation velocity of large deformation soft rock section by one time rigid support is much lower than that by flexible support; the maximum convergence velocity is reduced from 28 mm/d to 18 ram/d, and the maximum settlement velocity is reduced from 24 mm/d to 12.8 ram/d; and the deformation is much easier to control after stress release. （2） The primary support deformation crack can be effectively controlled, the tunnel structure quality can be guaranteed, and the successful passing through F7 main fault can be realized by adopting one time rigid support supplemented by optimized tunnel sidewall curvature and other construction methods.