Technical specifications

Scope of works:

• The ElbX Elbe crossing structure is part of the SuedLink grid expansion project, an approx. 700 km long 525-kV DC transmission line from Brunsbüttel in Schleswig-Holstein to Großgartach in Baden-Württemberg.
• It consists of a tunnel structure beneath the Elbe River and, on both sides of the Elbe, underground access and cable jointing structures as well as the associated above-ground operational buildings.
• A total of six high-voltage cables are to be passed under the Elbe. The client for the project is grid operator TenneT TSO GmbH.

Construction method

• The two access structures and the two cable jointing structures are to be built in excavations with a depth of up to approx. 25 m using the diaphragm wall method.
• The TBM tunnel with an internal diameter of 4.0 m is to be excavated by means of a slurry shield (or hydroshield) TBM and lined with a single-pass segmental lining, thickness 30 cm. In addition, short sections are to be constructed using the cut-and-cover method.

Geology

• artificial fill,
• Holocene deposits of the Elbe marsh (organic soft layers,
• mudflat sand, alternating layers of clay/sand),
• deposits of the Elbe meltwater valley (sands with gravel intercalations or gravel with rock intercalations),
• boulder clay,
• Lauenburg strata (silt/clay with fine sand), silty fine sands with boulder clay and mica clay.