Preserving Historical Structures in Urban Tunneling: Diaphragm Walls Embedded in Bedrock
Preserving Historical Structures in Urban Tunneling: Diaphragm Walls Embedded in Bedrock
The construction of the West Link tunnel in Göteborg, particularly in the Kvarnberget section, presented significant geotechnical challenges due to the presence of a thick layer of soft clay and a moraine layer with large boulders. To ensure stability and protect nearby historical buildings, a top-down excavation method was employed, with reinforced concrete diaphragm walls (D-walls) embedded into the bedrock. Given the variable depth and steep inclination of the rock surface, the diaphragm walls were anchored using small-diameter steel piles (D=120mm) and jet grouting injections to enhance load transfer and minimize differential settlements.
During construction, difficulties arose in achieving the intended connection between the diaphragm walls and the bedrock due to the heterogeneity of the moraine and high-pressure groundwater conditions. An initial attempt at jet grouting failed, necessitating adjustments in injection parameters and pre-cutting techniques. Subsequent testing verified the improved effectiveness of this approach. Structural analyses carried out confirmed the adequacy of the modified design in maintaining stability.
Monitoring of adjacent historical buildings, such as Nordstaden 13.12 and 13.7, indicated that vertical and horizontal displacements remained within acceptable limits, with no significant structural damage attributable to the excavation. The observed settlement trends align with historical patterns, suggesting that the mitigation measures effectively preserved the structural integrity of these buildings. This study highlights the success of combining deep foundation techniques with continuous monitoring in protecting historical structures during underground construction.
Keywords: diaphragm walls; top-down construction; jet grouting; steel micro-piles; moraine; historical buildings; monitoring; settlements.
Federico Capata; Matteo Iacorossi; Francesca De Santis
4th International Symposium on the Preservation of Monuments and Historic Sites
Heritage Sites and Urban Development
https://doi.org/10.53243/tc301-2026-4