Cityringen Copenhagen complex building protection for tunnellingin soft ground

Abstract: The existing metro system in Copenhagen has been expanded since 2011. A new 15.5 km long metro ring called "Cityringen" was constructed. At the new crossing station Kongens Nytorv, the tunnel passes above the existing tunnel and crosses under existing foundation with extremely short distance. After detailed risk analysis two main mitigation measures for the existing buildings were defined using compensation grouting and jet grouting. The historical buildings were supervised at all construction stages with permanent geotechnical monitoring systems.