郑万高铁大型机械化施工隧道位移控制基准研究

Study of Displacement Control Criterion for Large-scale Mechanized Construction of Tunnels on Zhengzhou-Wanzhou High-speed Railway

依托郑万高铁湖北段大断面隧道洞群,针对其开挖断面面积大、软弱围岩占比高、采用大型机械化大断面法施工的特点,开展初期支护位移现场监控量测,对监控量测数据进行分类统计、包络回归分析,得到Ⅳ、Ⅴ级围岩深、浅埋不同大断面法(全断面法、微台阶法)开挖下初期支护位移沿隧道纵向的函数表达式及各工况下分段位移占极限位移的比值。最后结合Q/CR 9218—2015《铁路隧道监控量测技术规程》中初期支护极限位移值,给出郑万高铁大型机械化施工隧道各工况下初期支护位移控制基准建议值。结果表明:郑万高铁隧道Ⅳ、Ⅴ级围岩采用深、浅埋不同大断面法开挖时,按距掌子面距离的分阶段位移控制基准相差较大,现行Q/CR 9218—2015《铁路隧道监控量测技术规程》中统一规定不合理;围岩级别、埋深及开挖方法相同时,拱顶沉降和洞周水平收敛规律基本一致。

The large cross-sectional tunnel group on Hubei Section of Zhengzhou-Wanzhou High-speed Railway has the features of large excavation cross-section,high proportion of weak surrounding rocks and large scale mechanized construction.Firstly,field monitoring on the displacement of primary support is carried out.And then the monitoring data are classified,summarized and analyzed to obtain the functional expressions for primary support displacement along longitudinal direction and proportions of tunnel displacement along longitudinal direction of each section under different conditions of large cross-section methods(full-section method and micro-bench method),different buried depth(deep buried and shallow buried)and different grades of surrounding rocks(GradeⅣandⅤ).Finally,the recommerded values of the primary support displacement control criterion for large scale mechanized construction of tunnels on Zhengzhou-Wanzhou High-speed Railway are proposed based on the ultimate displacement in Technical Specification for Monitoring Measurement of Railway Tunnel:Q/CR 9218-2015.The results show that:(1)The displacement control criterions according to the distance from tunnel face in different phases of tunnel on Zhengzhou-Wanzhou High-speed Railway are variable under different conditions,thus the standard ultimate displacement in criterion is unreasonable.(2)The laws of crown top settlement and tunnel surrounding horizontal convergence are consistent under different conditions of surrounding rock grades,buried depths and excavation methods.