Dublin Port Tunnel -Excavation of an 11.8m Diameter Urban Motorway Tunnel

摘要

Every year more than 2,000,000 heavy vehicles pass through Dublin Port. These vehicles contribute tornserious traffic congestion in the city centre of Dublin. The Dublin Port Tunnel has been planned tornconnect Dublin Port to the M1 Motorway and thereby remove 9,000 heavy vehicles a day from therncity centre. The twin tube road tunnel is approximately 4.5 km long with each tube having 2 lanes ofrncarriageway and a walkway for emergency exit and maintenance. Approximately 2.6 km of the totalrntunnel length of 4.5 km is being constructed by bored tunnelling whilst the remainder is being built byrncut & cover methods. The NMI Consortium was awarded the design and build contract in Decemberrn2000. The consortium consists of Nishimatsu, Mowlem (UK) and Irishenco (Ir.). Nishimatsu arernresponsible for the design and construction of all the civil works related to the bored tunnels andrndecided to use two different 11.8 m diameter TBMs mainly due to the differences in ground conditions.rnOne TBM for hard rock will excavate about 86% of the bored tunnel section in hard limestone andrnbelow densely populated housing areas. The second machine is an Open-Face TBM equipped with 2rnintermediate decks and 3 excavator arms for its 660 m drive in boulder clay. Both tunnels are linedrnwith a structural concrete segmental primary lining and an insitu concrete secondary lining thatrnprovides fire protection and a smooth finish.