ABSTRACT
The Brenner Base Tunnel is part of the TEN-T SCAN-MED corridor and allows the overcoming as a natural barrier of the Alpine ranges. The Isarco River Underpass represents the southernmost construction lot and links the Brenner Base Tunnel with the existing Brenner line and the railway station in Fortezza. The section will include civil works for the two main tunnels for a total length of roughly 4.3 km, as well as two interconnecting tunnels for a total length of 2.3 km that connect with the existing railway line. Construction will be extremely complex from a technical point of view: both the main tunnels and the interconnecting tunnels will pass under the Isarco River, the A22 motorway, the SS12 motorway and the Verona-Brenner railway line with a minimal leeway. The work is scheduled to be completed in 2023. The paper summarizes the design choices made for the construction of the underground works, with specific reference to the construction of the Isarco river underpass tunnels. The excavation will be performed with a very shallow cover, ranging between 5–8 m, very close to the river bed. It will start from shafts on the riverbanks, after ground improvement and soil freezing. The specific field test executed to define the grouting procedure will be focused on as well.
