大断面机械化施工隧道二次衬砌支护时机研究

Study on Supporting Timing of Secondary Lining of Large Section Tunnel with Mechanized Method

为了合理确定二次衬砌支护时距掌子面的距离,文章采用实测初期支护断面位移稳定曲线回归分析与有限元数值分析相结合的方法,以距掌子面距离作为二次衬砌安全支护的判定指标,建立了确定二次衬砌支护时距掌子面距离的理论计算方法。依托郑万高铁湖北段隧道群,对大断面机械化施工隧道初期支护变形稳定条件下二次衬砌支护时距掌子面距离进行研究,研究表明:取隧道施工安全储备系数为2.4,则Ⅳ深埋、Ⅳ浅埋、V浅埋条件下,分别在距掌子面13倍洞径、12倍洞径、7倍洞径时可进行二次衬砌支护。此方法为类似大断面机械化施工隧道工程建设提供了参考。

In order to determine the reasonable distance to the face when construction of the secondary lining,the method of combining the regression analysis of the displacement stability curve and the finite element numerical analysis of the initial support section is adopted in this paper.Taking the distance to the face as the judgment index of safe construction timing of the secondary lining,a theoretical calculation method for determining the distance from the face to the secondary lining was established.The distance from the face to the secondary lining under the initial support deformation stability was studied based on the tunnel group of the Zhengwan High-speed Railway Hubei section.the research shows that taking the safety reserve coefficient of the tunnel construction as 2.4,the secondary lining can be constructed at the location in where the distance to the face is 13 times,12 times,and 7 times tunnel diameter under the conditions of grade IV and deep depth,grade IV and shallow depth,and grade V and shallow depth.This method provides a reference for similar large-scale mechanical constructed tunnel.