An 8 m diameter Robbins Hybrid Single Shield/EPB tunnel boring machine (TBM) was launched to bore the tunnel in December 2013. The machine was built using Onsite First Time Assembly in order to fit within a tight project schedule. Assembly at the remote jobsite near Moranbah, Australia took about four-and-a-half months, and the machine was then walked down into a launch tunnel.
Two decline tunnels, at grades of 1:6 and 1:8, will be used for mine access to new coal seams. The hybrid machine is tackling mixed ground conditions ranging from sand and clay to varying types of sedimentary hard rock up to 120 MPa UCS, as well as coal seams.
Methane gas is expected to be present throughout the tunnel, so the machine has been designed as Explosion Proof Compliant to ERZ-1.
“Grosvenor is the first underground coal mine in Queensland to use a TBM for drift construction. We are proud to be pioneering this technology,” said Grosvenor Project Director Glenn Tonkin.
“We commenced tunnelling last month and the machine has advanced more than 100 m so far. We are on track to reach pit bottom in the next couple of months. The first few weeks were largely spent commissioning the machine in compliance with the mine standards. We expect the machine will perform well and we will achieve the planned cutting rates,” said Mr Tonkin.
The machine is expected to complete the first decline tunnel in April 2014.