背斜核部区隧道初期支护变形机理及支护对策

The Primary Support Deformation Mechanism and Supporting Measures for the Tunnel across Anticline Core Zone

为了给背斜核部区隧道设计施工提供参考和技术支持,文章针对周公山隧道K8+559～K8+527过背斜段开展了专项测试。测试结果表明:测试断面拱顶部位接触压力及变形较拱腰、边墙大;对比分析测试断面和验证断面结果,接触压力有所降低,说明采用"先让后抗"、适当增大预留变形量的方案有效合理;结合隧址区地质条件,认为隧道变形由其赋存的地质环境所决定,欠合理的施工方法及各不利因素的组合是其诱发因素;变形破坏过程可概括为:"开挖—卸荷—差异性回弹变形—离层—顶板简支梁式弯折破坏"。研究结果为理论分析提供了计算参数,为后续研究提供了基础数据,积累了复杂应力条件下特长隧道的设计施工经验。

In order to provide reference and technical support for the design and construction of the tunnel across anticline core area,special test was conducted at the section of K8+559-K8+527 of the Zhougongshan tunnel.The testing results show that the contact pressure at crown is larger than that of haunch and side wall at the test sections;a contrastive analysis on the results of test sections and verification sections was carried out and it was found the contact pressure deceases somewhat,which means the scheme of'support after release'and increasing reserved deformation is effective and reasonable;tunnel deformation is governed by the geological condition,unreasonable construction method and combination of various adverse factors are the inducing factors;the process of deformation and failure can be generalized as excavation—unloading—differential resilient deformation—layer separation—bending failure of the top roof as simply supported beam.The research results provide calculation parameters for theoretical analysis and also basic data for the following study,accumulating the experience for the design and construction of super-long tunnel in complex stress condition.