ABSTRACT:
The backdrop for this research paper is the tunnelling that is currently nearing completion 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 bore are also key considerations. 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 heterogeneous rockmasses. A discussion of the geological conditions, material property determination, monitoring data and the model calibration strategy is given. The focus is on the Driskos tunnel, the longest of the project.
1 INTRODUCTION
The Egnatia Odos Highway is a 680 km modern motorway that is currently under construction in Northern Greece. Egnatia Odos is part of the Trans- European road network of highways within Europe and follows the ancient Egnatia Road, constructed by the Romans in the 2nd century B.C. The new 680 km Egnatia motorway (Fig. 1) is a closed, dual motorway. Upon completion, the route will have a total of 73 twin road tunnels with an overall combined single carriageway length of 98 km. Sixty of these tunnels are bored or blasted tunnels. The remainder are cut-and-cover (Egnatia Odos AE 2001).
