Exceptional Use of Liebherr LRB 255 Piling and Drilling Rig in Quebec

In Montreal, a Liebherr LRB 255 piling and drilling rig owned by Centurion Fondation, Inc. is being used with a double rotary drive DBA 300 for the construction of an entry shaft for tunnel excavation. This application is relatively new in North America and is being executed for the first time in the province of Quebec.

On the island of Montreal, near the intersection of Rue Notre-Dame Est and Rue Alphonse D Roy, a tunnel with a length of four kilometres and an internal diameter of 3.6 metres is planned. After completion it will be used as a water main reaching from Montreal to the Rosemont Reservoir on Ile de Montreal. The Rosemont Reservoir was shut down in 1978 and is now being put back into service in order to ensure the supply of sufficient drinking water to the city.

The entry shaft for the excavation of the tunnel has an interior diameter of 11 metres. The entry shaft is being built using a compression secant pile wall made up of 74 intersecting piles, each with a diameter of 750 mm and a length of 22 metres.

The primary piles, used as filler, are installed first. Upon drilling of the secondary piles, the rebar cage is vibrated into the pile using an electric vibrator. The piles are drilled into a previously constructed template, ensuring their exact position. The soil consists of sandy clays and sandy tills with boulders and the piles are drilled approximately half a metre into the shale bedrock.

This project is the first jobsite in Quebec where an LRB 255, equipped with a DBA 300 double rotary drive, is being used. This application, also known as “cased CFA drilling”, has been chosen by Centurion Fondation due to the high productivity in installing the piles, thus reducing construction time and increasing the efficiency of the project.

The 670-kW Liebherr diesel engine of the piling and drilling rig provides the power that is required to operate the DBA 300 while at the same time maintaining excellent fuel efficiency. The 20-tonne Kelly winch and 45-tonne crowd force ensure that the soil filled auger and casing are pulled out of the ground, while the concrete is being pumped through the hollow stem to underneath the auger. With this method, there is no cave-in and the quality of the piles is guaranteed.

The machine operator can monitor the process on the Liebherr process data recording system PDE in the cabin. This system, with a large display, shows the operator the constructed pile size on the screen and records all relevant pile parameters, such as concrete pressure, concrete volume and depth.