ABSTRACT
The use of underground space has become of great importance in the development of sustainable infrastructure projects, especially in urban environments. In this context, the present paper focuses on the case study of the West Link project in Gothenburg section E03, describing the key design elements of the cut&cover tunnels, monitoring data and the main challenges faced during design and construction. The excavation for the cut&cover tunnels has been particularly challenging due to the significant depth of excavation (up to 18m), the geotechnical conditions ranging from soft plastic clay to hard bedrock, sensitive groundwater level, the presence of surrounding historical buildings and the limited construction site area. Sheet pile excavation and top-down construction with diaphragm walls, have been separately adopted according to ground conditions, allowing to reduce ground movements, minimise the use of temporary elements and maximise site area.
Innovative elements for large construction projects were introduced to safely carry out the excavation. Deep Soil Mixing (DSM) was extensively used to improve soil mechanical properties, reducing ground movements and structural forces and improving passive resistance and safety against basal heave failure. Also, selected d-walls were extended to reach the bedrock level in order to provide sufficient bearing and shear capacity during both short and long-term conditions; at such locations, jet-grouting injections and steel core piles were adopted to enhance connection of the d-wall toes into the bedrock.
Finally, groundwater control measures have been put in place to ensure safe excavation and construction. The project was completed in mid-2024 and monitoring data were available all time to control the construction process.
