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Tunneling Bentonites from Imerys offer several key advantages for tunneling in loose permeable soils that contain high levels of sand and gravel and where soil pressure or hydrostatic pressure can lead to the collapse of the cutting front. In these conditions, a specialized slurry shield, known as a hydroshield, is created to support the face.
This process, which involves developing a filter cake to transfer the pressure, can be employed in the construction of road or railway tunnels, sewage tunnels, sewage canals, mining shafts or power plants and hollows.
Beyond just supporting the tunnel face, our Tunneling Bentonites used with the hydroshield technique offer the following additional advantages:
- Air-pressure-stable filter cake enables inspection of the face or broaching works in the cutter chamber.
- Pumps transport overburden in a flushing circle to the separation plant.
- Dissolved soil remains in suspension, even when machines are still
- Friction and wear on cutters is reduced.
- Soil zones in the surrounding annular areas are sealed.
The 4th pipe of the Elbe Tunnel in Hamburg is one example of the successful use of our Tunneling Bentonite.