X-Ray Laser European XFEL, Contract Sections 1 + 2

At the end of 2008 the Deutsche Elektronen Synchrotron (DESY} a JV under the technical management of the Hochtief Construction AG was commissioned with executing the planning of and producing underground structures (combined contract sections 1 and 2) for the European XFEL X-Ray Laser (XFEL stands for X= X-Ray and FEL = Free Electron Laser). These structures are being built for a research facility, in which ultra-short x-ray laser flashes (30,000/sec) are produced at an intensity, which is a billion-times higher than the best x-ray sources of a conventional nature. In order to create these x-ray flashes electrons are subjected to high energies and subsequently guided by specially arranged magnets. In the process the particles emit light, which becomes increasingly stronger until an extremely short and intense x-ray flash is produced. Thanks to these highly intensive, ultrashort x-ray flashes scientists are able to film chemical reactions such as e.g. how molecules are formed or decipher the atomic structures of bio-molecules and materials. The facility possesses features that are unique throughout the world thus opening up new research opportunities for scientists and industrial users. The bulk of the European XFEL runs underground. The 3.4 km long tunnel route stretches from the DESY in Hamburg-Bahrenfeld towards the north-west, gradually forks off into five tunnels and ends up in the town of Schenefeld in Schlesvig-Holstein. An experimental hall is being set up there, in which international teams of scientists will carry out their experiments with x-ray flashes. A shaft is set up at each tunnel junction. Contract section 2 consists of the accelerator tunnel, the first junction structure, followed by two so-called undulator tunnels as well as the next two junction shafts. The tunnels branch off further in contract section 1. Altogether the project constitutes eight tunnel sections, three junction structures and the experimental hall. The contract sect ion 2 tunnels possess a bored diameter of 6.17 m and are 2,011, 480 and 594 m long. The bored diameter of the eight tunnels in contract section 1 amounts to 5.48 m with lengths varying from 661 to 137 m. All the tunnels are being driven by a hydro-shield and secured by means of 30 cm thick reinforced concrete segments. They run mainly through sand/gravel and glacial marl. The many accesses and exits are a feature of the tunnelling operations. This is where the Hochtief Construction AG's patented “flying start-up” comes into play. A hydraulically controlled back-anchoring system, which advances in conjunction with the shield tunnelling machine, replaces the conventional rigid structure and the blind segmental tube. In this way optimised space conditions are attained in the shaft. Interruptions as well as costs caused by blind segments do not ensue. The total of seven shaft structures are to be produced in the form of diaphragm wall excavation pits with back-anchored underwater concrete base. The pits possess dimensions of up to 92 x 52 m and extend down to a depth of 28 m.

Country: Germany
Region: Hamburg/Schlesvig-Holstein
Tunnel utilization: Utilities
Type of utilization: Research Facility
Client: DESY (Deutsches Elektronen-Synchrotron Hamburg)
Consulting Engineer: Ingenieurgemeinschaft WTM/ Amberg
Contractor: Hochtief Construction AG/Bilfinger Berger AG
Main construction method: Trenchless
Type of excavation: Shield machine (SM)
Lining: Reinforced concrete segments
No. of tubes: 8?
Tunnel total length: 5,777 m
Cross-section: 4.60/5.30 m (Internal diameter), 5.48/6.17 m (bored diameter)
Contract Volume: approx. 206 mill. euros
Construction start/end: December 2008 till May 2013
Opening: 2014