American’s Grosvenor Project in Moranbah, Central Queensland is using a Tunnel Boring Machine (TBM) to construct a drift for coal mining. This method results in better quality drifts, enhanced safety and faster delivery.
In partnership with Redpath Mining, Rocla (ACP’s parent company) were asked to provide access for two incline access portals:
- Conveyor drift (transports coal from the underground long wall to the surface stockpile)
- Transport drift (equipment and worker access to underground operations).
“Two Super•Cor® structures with a clearance envelope large enough to allow an 8m diameter TBM to be passed through it were designed and used on this project,” says Patrick Jones, SEQ Region Sales Engineer.
“The Super•Cor® structure’s large annular corrugation (381mm pitch by 140mm depth) provides nine times the stiffness of structural plate. Its superior strength and lightweight construction made it a more cost effective solution to a concrete structure.”
Two structures were supplied to the project: Conveyor Drift Portal Super•Cor® structure arch 381-53S:8908mm span by 8050mm rise by 117m long and Transport Drift Portal by 167m long.
The TBM is assembled and passed through the Super•Cor® structure down to the highwall, where it begins boring into the ground creating a 7m-diameter tunnel. The TBM descends at an angle of 1V:8H and 1V:6H until it reaches the depth of the coal seam at around 160m below the surface. As the TBM moves forward, precast concrete ring segments are installed to line the inside of the tunnel to prevent collapse.
Project at a Glance:
- Anglo will spend approx. $US1.7b on the Grosvenor mine
- The TBM broke ground late in 2013 and will be recovered and used to bore the transport drift at a later date
- The project started mid 2012 and will need more than 3,000,000m³ of earthmoving and more than 30,000m³ of reinforced concrete