Hydro-demolition Efficiency in Tunnel Repair Solution - continued
Bageci tunnel project manager Luc Bosmans said:
Due to the special safety and environmental demands and lack of space, hydrodemolition was really our only option from the very start. We thought it was going to be the most productive method for this tunnel work, and it proved to be very efficient.
In total, the Conjet Robot 365, together with the Hammelmann pump operating up to a pressure of 1200 bar, worked 1,370 hours in the Biéreau tunnel and selectively removed 1,610 m³ of defective concrete from the tunnel circumference at an average depth of 80 mm to 100 mm. The total area treated was approximately 17,000 m².
Bageci also removed the concrete debris, damaged rebar and applied new high quality concrete on the tunnel lining.
This restoration has been completed in 220 days with the Conjet Robot demolishing and removing concrete at a rate of about 1.35 m³/h. In my opinion this is an excellent result
said Luc Bosmans.
Bageci site manager, Sandro Bonsiambiante, added:
Throughout the tunnel the concrete has been harder and more resistant in some places, but with the auto regulation the Conjet robot selectively demolished and removed only the damaged concrete to the right depth over the entire surface.
Another advantage was the high availability of the equipment. There is a lot of environmental dust and wear and tear on equipment in this kind of application and the spare parts supply has been excellent with no serious break downs.”
The Conjet Robot 365 consists of a carrier that includes pulse monitored drive wheels, electric and hydraulic systems and a simple, easy to use control system. The carrier can be equipped with optional attachments, such as standard feed beam, tower or a rotor assembly and can also be operated by a wireless control.
The cutting head features a 45º attack angle of the jetting lance as standard, variable oscillation width and encoders for lance turning and cradle position.
Relining the Tunnel
Bageci chose, after consulting Grouttech, a dry mortar projection technique to reline the exposed reinforcement. The client had previous positive experience using this system due to its unmatched quality and ease of application.
By applying the grout, under high pressure, through a capillary nozzle, Grouttech ensured a high quality shotcrete (C45) injection was achieved. Two 30 t. capacity batch silos were installed on flatbed rail wagons to provide a close supply system. This enabled maximum use of time as the work continued 24 hours a day.