Construction of the US$304M, 5.7km long maze of 11 tunnels for the US$1.4bn European X-Ray Free-Electron Laser project (European XFEL) in Germany has been completed. The complex network of tunnels between Hamburg-Bahrenfeld and Schenefeld in Schleswig-Holstein were built by the ARGE Tunnel XFEL JV comprising Hochtief and Bilfinger Berger using two Herrenknecht Mixshields, of 6.17m and 5.45m diameter erecting a segmental lining through boulder clay, sands and gravel.
Prof. Massimo Altarelli, Managing Director of European XFEL GmbH commented, “The construction of the tunnels is one of the most difficult building phases. We are glad that this task could be completed according to plan and that we could keep costs within the tight budget targets we set at the time the contract was awarded. We would like to thank the personnel of the participating construction companies for their good work. Their commitment helped us take a big step forward to reach our scientific goals. We scientists will do our part to make sure that this facility provides excellent research opportunities when it opens in three years.”
Ullrich Reinke of the Executive Board of Hochtief Solutions AG said, “The Hochtief and Bilfinger working group will demonstrate in Hamburg that complex engineering structures can be carried out within a partnership-based collaboration with the client, in due time and within budget.”
Tunnel construction began in July 2010 with the 6.17m diameter Mixshield ‘TULA’ which bored the first three drives, XDT 1 (480m), XDT 2 (549m) and XDL (2010m). Tunnelling with TULA was concluded in August last year.
In January 2011, the 5.45m diameter second machine, AMELI started excavation of an array of short drives, XTD 9 (544m), XTD 10 (220m), XTD 4 (300m), XTD 8 (361m), XTD 7 (141m), XTD 5 (200m), XTD 3 (267m) and XTD 6 (660m).
Tunnelling was logistically complex given the special layout of the project, the 160 tonne machine had to be repeatedly relocated and re-prepared for boring. Tunnelling was officially concluded on June 14th.
The European XFEL, which is due to open in 2015, will generate ultrashort X-ray flashes – 27 000 times per second and with a brilliance that is a billion times higher than that of the best conventional X-ray radiation sources. The facility will open up completely new research opportunities for scientists and industrial users.