ABSTRACT
During construction of the Thessaloniki Metro Project, the TBM-bored tunnels had to cross an active geological fault. This case study presents the design and construction of a special segmental lining that was implemented. The possible movements of the fault were evaluated according to geological investigation data. After examining alternative solutions, the Projects Authority ATTIKO METRO S.A. concluded to proceed with using an innovative system of seismic joints between the tunnels’ concrete rings. 3D FEM analysis was used to obtain tunnel stresses and displacements due to the estimated fault movements. It was shown that boring the tunnels through the fault with EPB-TBMs was feasible but required certain modifications of the segments’ steel reinforcement and the use of special seismic connectors. Extensive laboratory tests verified the proper behavior of the proposed system. Fabrication and installation of the special segments in the tunnels have been successfully completed.
