Athens Metro Line 3: Complex Tunnel Geometries: Fid-Bau Portal

Athens Metro Line 3: Complex Tunnel Geometries

Schina, S. / Charalampidou, A.

Abstract Complex tunnel geometries are very common during the design of urban tunnelling and especially metro lines. Relevant complexities were common during the construction of Athens Metro in Greece, where the need of giving access to trumpet areas, multi-storey underground constructions and transition zones produces special design requirements. Characteristic case histories are the trumpet area as well as the access gallery and chamber to Egaleo Station in the same extension, which are presented in the paper. In both cases, the real challenge was to give solution to underground complex constructions within short lengths of different tunnel profiles. In the first case, a triple-track tunnel splits to a single and a double-track one, while on the second one, a three-storey access gallery was constructed at the north side of Egaleo Station in order to give access for the construction of the station. According to the geology in the area, the Athenian schist was expected, completely weathered on the top and from low to medium strength deeper. The main criteria of the design was to result to a construction methodology such as to assure stability, low surface settlements and convergences, safety, quality and construction advance, within a realistic solution to the constructor. In both cases, the conventional tunnelling method was applied with success, not only regarding the final surface settlements which proved to be small, but also the speed and the convenience in applying on site the designed procedure.