Preparing for new sets of nuclear physics experiments at the XFEL European research facility in Hamburg, Germany, was the task of two Herrenknecht Mixshields that completed work in early June. The two machines of 6.16m and 5.45m diameter were relaunched several times to complete the eleven drives for a total of 5.78km at the research center DESY in Hamburg between Bahrenfeld and Schenefeld in the district of Pinneberg (Fig 1).
Fig 1. Schematic of the tunnels excavated by the two Herrenknecht Mixshields
The two Mixshields, named TULA, (short for Tunnel for Laser) and AMELI (meaning Am Ende Licht or Light at the End), were used by contractors Hochtief and Bilfinger Berger to excavate the complex of tunnels.
Tunnelling started in July 2010 and by late July 2011, TULA had completed successfully its task for the more than 2km long main tunnel and the two further 600m long sections.
Following that, AMELI completed the headings at the end of the main tunnel, which required moving the machine three times through a shaft and lifting it out of the shaft four times for relocation.
In order to keep the Mixshields exactly on course, both machines were fitted with a laser-guided navigation system from Herrenknecht group company VMT.
Launch of the TULA TBM on the main drive
Prof Dr Helmut Dosch, Chairman of the Deutsche Elektronen-Synchrotron DESY Board, head shareholder of the European XFEL GmbH, expressed satisfaction at the final breakthrough when the AMELI TBM entered its last target shaft. "Completion of tunnelling on time has enabled us to achieve a key milestone for this unique research facility." There is nothing now stopping installation of technical infrastructure and nuclear particle accelerator components.
As of 2015, electron and x-ray light will be flowing through the European XFEL (X-Ray Free-Electron Laser) research laboratory system. Up to 27,000 ultra-short laser flashes per second will be generated in the x-ray range by XFEL giving rise to entirely new research opportunities for physicists, biologists, chemists, doctors and material scientists.
AMELI machine ready for dispatch.....
.....and making its final breakthrough
"Technically, the tunnel system was extremely complicated," reported Technician Steffen Benad of Herrenknecht, who provided support at the job site in Hamburg. "Just imagine how large this structure is and then how small the light beam will be at the end."
Table 1. Key Herrenknecht projects in Hamburg
First Mixshield delivered for the Hadron-Elektron-Ring-Anlage (HERA)
Tunnel length: 6,300m
Mixshield Trude completed the 4th tube of the highway crossing under the Elbe River
Tunnel length: 2,560m
Excavation of sections on the S1 suburban railway to Hamburg Airport
Tunnel length: 3,413m
Mixshield completes drives for the Hamburg U4 metro line from the Elbe River towards the Alster
Tunnel length: 5,620m
"Tunnelling was one of the most difficult areas of the construction," said Prof Dr Massimo Altarelli, CEO at European XFEL GmbH. "We are delighted that this work is being completed on time."
Herrenknecht has a long association with tunnelling projects in Hamburg, each associated with various innovations. For the first time in 1985, Herrenknecht supplied a Mixshield to Hamburg for the construction of the HERA (Hadron-Elektron-Ring-Anlage) elementary particle accelerator. This was the first machine to progress safely in soil containing excessive ground water. In 1997, Herrenknecht supplied the world's largest Mixshield at the time for excavation the 4th Elbe Tunnel tube.
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