ABSTRACT
this paper describes the complexity of the excavation of the Athens Metro Line 3, Extension Haidari-Piraeus, including a 6.5km double track tunnel with a 9.48m diameter EPB TBM. The EPB TBM Ippodamo has completed its journey in approximately 4 years. The project includes six new stations. Maniatika Station is the only one built below surface in cavern while all the other ones through cut and cover. The mainline also sees the construction of eight ventilation shafts and two NATM sections, double and triple tracks, at the assembly and disassembly shafts for overall 340m. The Athens TBM has excavated through a densely populated urban area in one of the oldest cities in the world. Due to the geological, hydrogeological, and geotechnical conditions, an EPB TBM has been chosen based also on specific needs, such as avoiding disturbance and causing damage to buildings and structures located within the zone of influence. Through the limestone section, Karstic voids of large dimension have been encountered and from both surface and the tunnel face, these have been successfully treated and filled. Working below the water table, in extreme proximity to the highly congested Piraeus harbor, has been an incredible challenge completed and executed in a highly professional way. Furthermore, the progress of the works has been also affected by the difficult economic situation of the country during the period.
