Tunneling
LKAB Wassara’s W120 water-powered hammer played a decisive role in the making of the tunnels going under the river Isarco, near Fortezza in Italy.
Fortezza, Italy
WeBuild SpA
W120 Hammer, with integrated check valve
The Brenner Base Tunnel is one of Europe’s most comprehensive and important infrastructure projects in modern time.
LKAB Wassara’s W120 water-powered hammer played a decisive role in the making of the tunnels going under the river Isarco, near Fortezza in Italy.
Background
The Brenner Base Tunnel (BBT) is the main segment of a new railway line that will connect Munich with Verona. BBT runs between Innsbruck and Fortezza. The new tunnel will lead to an improvement for, above all, the truck traffic through the so-called Brenner Pass. The two-tube tunnel system will be 55 km long, making it the longest underground railway stretch in the world.
Columns were made with the Wassara W120 hammer
The columns were made up to 40m in one single pass. LKAB Wassara’s W120 water-powered hammer with a Ø152mm drill bit was used for this. Above the W120 hammer a monitor was mounted. The monitor worked both as a nozzle holder for the Jet-grouting and a flow diverter that diverts water from the water channel in the drill pipe to the hammer.
The monitor is of a double flow type where compressed air is used to improve the performance of the jet-grouting. The water, air, and jet grout are supplied through a 127 mm triple wall drill tube securing that the fluids are not mixed.
| DTH Hammer | W120, with integrated check valve |
| Drill bit | Ø 152 mm |
| Drilling fluid | Clean water |
| Drill rods | Triple fluid 127 mm, CRM |
| Rig | SM 28, Soilmec |
| Monitor | Double fluid air/grout, CRM |
| Swivel | Grout-Water-Air, CRM |
| Water pump | Electric 400 L/min, 180 Bar, PTC |
| Jet-grout pump | Tecniwell model TW352 |
| Borehole length | Up to 40 m |
| Total meters drilled/grouted | 250 000 m |
| Geologic formation | Loose deposits, gravel, rounded sand, boulders and large granite blocks |
| Project time | 2018 and ongoing (per March 2022) |
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