July 19th saw Herrenknecht hand over a 4.9m diameter Mixshield TBM to the client that will be used on a 5.2km long tunnel that crosses under the River Elbe, as part of the SuedLink grid expansion project that when complete will transport electricity over 700km from Brunsbüttel in Schleswig-Holstein, northern Germany, to Großgartach in Baden-Württemberg, southern Germany.
SuedLink is one of several extra-high-voltage direct current (HVDC) transmission lines planned in Germany. The “electricity highway” is intended to connect the wind power regions of northern Germany with the industrial locations of Bavaria and Baden-Württemberg in southern Germany.
For this to succeed, the first step is the crossing under the Elbe River. This section is considered key for the underground cable line. The consortium, ARGE Tunnel ElbX, is building an approximately 5.2km long tunnel from Wewelsfleth (Schleswig-Holstein) to Wischhafen (Lower Saxony) on behalf of the transmission system operator TenneT.
The tunnel will accommodate six 525kV underground cables and the associated building, safety, control and monitoring technology as well as rails for the tunnel vehicles required for maintenance and repairs.
Herrenknecht received the order from the ARGE Tunnel ElbX JV, consisting of PORR GmbH & Co. KGaA and Wayss & Freytag Ingenieurbau AG, for a TBM specially designed to meet the project requirements. On its way under the Elbe River, it will encounter varied geology consisting of clay, peat, sand, gravel as well as stones and boulders.
Johannes Faißt, Project Manager at Herrenknecht explains, “The ElbX Tunnel with it heterogeneous subsoil, high water permeability and the water pressure under the Elbe is a special challenge that spurs us and our technologies on.”
The highly complex Mixshield is sealed against the water pressure 20m below the Elbe using a multiple sealing system. The TBM is lining the tunnel with prefabricated concrete segments to an inner diameter of 4m and an outer diameter of 4.6m.
After the factory acceptance, the machine will be dismantled, transported to Schleswig-Holstein, lifted into the shaft excavation shaft in individual parts and assembled.
The TBM is due to start work towards the end of this year.
Herrenknecht
Pioneering Underground Technologies - Herrenknecht AG is the technology and market leader in mechanized tunnelling. As the only company worldwide, Herrenknecht delivers cutting-edge tunnel boring machines for all ground conditions and in all diameters - ranging from 0.10 to 19 meters.
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