Gothenburg Marieholm Tunnel

In the urban area of Gothenburg, the Marieholm tunnel passes beneath the river Göta Älv. The construction method chosen to build the motorway tunnel was an immersed tunnel. Large and deep excavation pits were built on both sides of the river. On the Marieholm side, the excavation pit was also used as a dry dock. Solexperts AG was commissioned by Züblin Scandinavia to develop a measurement concept for geotechnical monitoring and to implement it in close cooperation with the site managers.

Measurement concept

During the construction of the excavation pits and the driving of the piles, large deformations in the subsoil were expected. This was due to the slightly overconsolidated, soft clay, which was up to 100 m thick. In addition, there are sensitive buildings in the immediate vicinity of the construction site. Comprehensive monitoring with elaborate instrumentation of the immediate surroundings of the excavation pits and the neighbouring building complex was necessary. Dozens of high-precision automatic inclinometer (IPI) chains with a length up to 50 m were installed, which measure with rotation by an internal motor to compensate for drift and temperature. Reverse head extensometers were used to measure heave and settlement of the excavation base during the various load changes of the different construction phases. In addition, pore water pressure transducers, settlement transducers and stress/strain sensors were installed.

Realisation

More than 1500 sensors were connected to around 65 data loggers on the extended construction site. A WebDavis database was set up to manage the data and prepare it for presentation on the web. In addition, WebDavis was used to link and calculate different data sets and to send alarm signals in case of critical conditions.

Downloads

Bridge monitoring

Munich 2nd main line (S-Bahn), Marienhof construction lot

Roche Basel

Lyon, Quartier Part Dieu Instrumentation of underground structures

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