Numerical Analysis of the Segmental Supporting System Under Earthquake Loading

Today, precast concrete lining (segmental) are used as system maintenance in the majority of tunnels excavated by TBM. On the other hand, the mechanism of the joint between two segments is not known under seismic loads. In this paper a numerical study about the effect of the earthquake on the segmental supporting system and the resultant vertical and shear forces on the contact surface between two segments is investigated. The Tehran -Karaj water conveyance tunnel (Amirkabir) was used as a case study. In this study, the UDEC software was used. At the first step, the segmental lining were simulated under no slip and full slip conditions and the normal and shear forces were studied. Finally, the effect of joint stiffness between two segments were investigated. Results showed that with increasing the interface properties, the normal and shear forces in the segmental joints increased. Also with increasing the joints stiffness, the normal and shear forces on the joints increased and the normal and shear displacement decreased. In other words, the rigidity increament of supporting system is associated with flexibility decrement of lining with respect to rock medium. So, the stresses increased and displacement decreased.