Lessons Learned Spanning 2 Decades of Tunnelling Experiences in Greece 

Full Name: Nicholas Vlachopoulos

Academic Affiliation: Royal Military College of Canada / Queen’s University

Position: Associate Professor

Abstract: The backdrop for this research paper/presentation is the major road and rail tunnelling construction that is currently occurring throughout Greece as well as the tunnelling that has been completed in the Epirus and Western Macedonia regions of Northern Greece, as part of the Egnatia Odos Highway construction. Highly deformed and altered sediments and low grade metamorphic rock masses dominate the near surface environment creating a variety of technical challenges for tunnelling. Accurate equivalent rock mass performance predictions for tunnels in these materials (including yield and residual strength as well as flow and dilation considerations) is complicated by geomorphologic peculiarities (mixed face conditions, variable orientation or rock masses and structure) such as flysch materials. In addition, portal stability problems, and geometrical issues such as the effects of simultaneous twin tunnel excavation on radial displacements of each tunnel bore are also key considerations at the design and construction stage of the tunnelling process. This work involves the use of 2D and 3D research models of tunnel sequencing for numerical simulation of composite material behaviour and sequential tunnel deformation response with a goal to investigating the strength and deformation of the heterogeneous rockmasses found in Greece; this is complimented with real data obtained from the field in Greece. As well, the use of a state-of-the-art fiber-optic probe that has been developed for tunnels in Greece will also be highlighted. Site-specific considerations and results pertaining to geological conditions, material property determination, tunnel monitoring data and the model calibration strategy will also be incorporated.