Investigation on the Deformation of Segment Linings in Cross-Fault Tunnel Considering the Creep Behavior of Surrounding Rock during Construction-Operation Period

Abstract

Time-dependent deformation of surrounding rocks during construction and service directly affects the structural safety of hydraulic tunnels. Specifically, the creep effect on the cross-fault diversion tunnels is particularly significant. In recent years, a variety of research has focused on the impact of creep on operating cross-fault diversion tunnels. However, there is a lack of consideration for the creep phenomenon during the construction-operation period. This study proposes a simulation method of segment linings deformation of cross-fault diversion tunnel combining deformation monitoring, creep constitutive identification, and creep during construction operation. According to the measured time-displacement data of the surrounding rock, the suitable creep constitutive model is selected by a regression-comparison method. Subsequently, the three-dimensional numerical model of the cross-fault tunnel is established, with the tunnel excavation and long-term creep calculation carried out under the creep effect of the surrounding rock. In addition, the intelligent inversion model was adopted to obtain the basic parameters of the surrounding rock. The results show that fault directly affects the rock mass characteristics near the fault. The radius of influence is about one time the tunnel diameter from the fault. The vertical deformation of segment linings of the vault and inverted arch tends to be subsidence when the fault is above the tunnel; however, the trend is inverse when the fault is under the tunnel. This work gives targeted engineering suggestions and provides a scientific basis for designing and constructing diversion tunnels under complicated geological structures.