CASE STUDY ABOUT STABILIZING WORKS IN HIGH SENSIBLE QUICK CLAY AREA IN MOSS, NORWAY

Since railway traffic is constantly increasing, BANE NOR (national railway of Norway) is building, renewing and expanding it’s railway network, especially in the greater area around Oslo. One of these projects is located in the city of Moss (appr. 60 km south of Oslo) that contains around 10 km of newly built double tracks north and south of the city (in tunnels and above ground) and a new railway station in the city center of Moss. During the first phase of the project it was discovered, that the underground in the center of Moss contains layers of quick clay making the area very sensitive for construction works. Following a redesign of the geotechnical works combined with a test field it was concluded that the soil stabilizing works can be done by installing jet grout columns to increase the slope stability. During execution of these jet grout works a lot of challenges were encountered such as reacting to the ground movements, adapt the jet grout works to the different soil layers or balancing the execution within aspects of economic terms while fulfilling highest quality requirements. Between September 2023 and October 2024 a majority of the stabilizing works in the city center of Moss could be finished preparing the ground for following geotechnical as well as construction works such as relocating streets, bored piles as a retaining wall or building the support walls for an excavation pit for the upcoming connection of the tunnels with the railway station.