无中导洞法双连拱隧道后行洞施工力学行为及参数优化分析

Analysis of Construction Mechanical Behavior and Parameter Optimization for Subsequent Tunnel Tube of Double-arch Tunnel without Middle Drift

为研究无中导洞法双连拱隧道后行洞施工力学行为及支护时机、空间效应的影响,以宜金高速黄角坪隧道工程为依托,采用数值计算方法,对后行洞不同开挖进尺、不同台阶长度和不同左右导洞掌子面错距等参数进行深入研究,进一步分析这些参数对后行洞围岩位移、初期支护受力特征和先行洞二次衬砌受力特征的影响。结果表明:随着开挖进尺、台阶长度和左右导洞掌子面错距的增大,后行洞的围岩位移、初期支护主应力和先行洞二次衬砌主应力均显著增大;台阶长度和左右导洞掌子面错距对后行洞初期支护和先行洞二次衬砌主应力的影响非常显著,在实际施工中应严格控制。

In order to study the construction mechanical behavior of the subsequent tunnel tube and the influence of the supporting time and spatial effect of double-arch tunnel without middle drift,based on the Huangjiaoping doublearch tunnel project of Yi-Jin Expressway,numerical simulation method is adopted,and the construction parameters such as excavation advance,bench length and different staggered distance of left and right faces of the subsequent tunnel are studied.The influence of these parameters on the displacement of surrounding rock,the mechanical characteristics of the initial support of the subsequent tunnel and the secondary lining of the advanced tunnel is further analyzed.The results show that with the increase of the excavation advance,the bench length and the staggered distance of left and right faces of the subsequent tunnel,the surrounding rock displacement,the principal stress of the initial support of the subsequent tunnel and the principal stress of the secondary lining of the advanced tunnel increase dramatically.Among them,the bench length and the staggered distance of left and right faces of the subsequent tunnel have significant effect on the principal stress of the initial support of the subsequent tunnel and the secondary lining of the advanced tunnel,and both shall be strictly controlled in actual construction.