Metro Thessaloniki: Tiefe Baugruben in Deckelbauweise

Thessaloniki Metro: Deep excavations by the top-down method.

The new Thessaloniki Metro has been under construction since 2006. The total length of 9.6 km includes, beside the excavation of two tunnels, the construction and support of deep excavations for 13 stations with central platforms. In order to reduce traffic disturbance and to minimize settlements in the neighbourhood, a top-down construction method with diaphragm walls was adopted. Due to the limited space availability, stations were constructed without an inner lining. Further difficulties are associated with the soft inhomogeneous subsoil, the large excavation depths below the groundwater level and the seismicity at the site. Starting with a project description, the paper briefly presents the geotechnical design for two typical stations and the measures taken for providing safety against uplift. Measured and predicted system responses are also compared.