Abstract:

The secondary lining of the mentioned tunnel is cast shortly after the installation of the preliminary lining. In order to investigate the variation rules of the internal force of the tunnel lining, the influence of tunnel excavation, surrounding rock mass creeping and tunnel lining rigidity on the axial force of the rebars in the secondary lining is studied on basis of the axial force monitoring records and construction records. The variation of the axial force of the rebars in the secondary lining can be divided into two stages, which meet the hyperbolic rule. In the first stage, the variation of the axial force of the rebars in the secondary lining is mainly affected by the tunnel excavation and the lining rigidity. The axial force increases significantly and reaches stable in one year because of the significant creeping of the surrounding rock mass. The first stage lasts for 33 days before the rigidity of the tunnel lining is formed. Then the variation of the axial force enters the second stage. In the second stage, the variation of the axial force of the rebars in the secondary lining is mainly affected by the creeping of the surrounding rock mass.

Key words: tunnel lining, axial force of re bar in secondary lining, time dependent rule, monitoring records