Basel - Muttenz unbundling: retaining walls and excavations

The project perimeter extends from Basel freight station to Muttenz. A new track will be built between the St. Jakob football station and Muttenz railway station. This will run partly on an embankment and cross a highway feeder road and the main SBB line on a new bridge. Several large angular retaining walls and noise barriers have to be built along the feeder tracks. In a first step, retaining wall structures in the form of anchored soldier pile walls and soil-nailed walls will be constructed along the tracks, in some cases during night and weekend closures. Subsequently, the retaining structures adapted to the respective ground conditions are constructed.

Classic angled retaining walls with and without brackets are used if the subsoil has good load-bearing capacity. We have developed special spur foundations for retaining walls on slopes due to the high earthquake load. On the project section with karstic subsoil, we had to counter the risk of sinkhole formation. We did this by structurally designing the retaining walls to withstand the subsidence of a section of ground. In addition, the base of the retaining wall will be monitored using fiber optic cables during use. In the area with soft siltation sediments, the retaining walls are completely founded on permanent micropiles so that the load can be transferred to layers with better load-bearing capacity and wall deformations can be minimized.