偏压连拱隧道洞口段二次衬砌施工时机探讨

 针对富溪隧道左线出口段在围岩变形尚未稳定的情况下能否进行二次衬砌施工的问题，根据隧道变形监测结果推测衬砌施工后隧道的剩余变形，并据此计算出衬砌结构的内力和安全系数。结果表明，衬砌施工后产生的变形大小对其内力和安全性影响较大。若衬砌结构变形仅为剩余变形的6.5%，其安全性能够得到保障。现场监测结果表明，衬砌施工后内部应力普遍较小，未超过混凝土强度。这说明在围岩变形没有完全趋于稳定的情况下，只要能够保证衬砌施工质量，可以提前施作二衬。

Discussions on Installation Opportunity of Secondary Lining for Portal Section of Asymmetrically-loaded Double-arch Tunnel

In order to determine the installation opportunity of the secondary lining for the exit section of the left tube of Fuxi tunnel when the deformation of the rock mass is still unstable, the internal forces and safety factors of the lining structure are calculated on basis of the residual deformations of the tunnel that are estimated from the measured results of the tunnel deformation. The results indicate that the magnitude of the deformation occurring after the installation of the lining has great impact on the safety and internal forces of the lining structure. If the deformation of the lining is only 6.5% Of the residual deformation, the stability of the secondary lining can be guaranteed. It is found that the internal stress of the lining obtained by means of field monitoring is smaller than the strength of the concrete lining. It is concluded that the secondary lining can be installed when the deformation of the rock mass is still unstable, provided that the construction quality of the lining can be guaranteed.