Hybrid TBM takes on Australian Decline Tunnel
March 5, 2014
On Dec. 20, 2013, an 8.0-m (26.2-ft) diameter
Two decline tunnels, at grades of 1:6 and 1:8, will beused for mine access to new coal seams. The hybrid machine is tackling mixedground conditions ranging from sand and clay to varying types of sedimentary hard rock up to120 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. “Grosvenoris the first underground coal mine in Queensland to use a TBM for driftconstruction,” said Glenn Tonkin, Grosvenor Project Director. “We are proud tobe pioneering this technology.”
In EPB mode, the machine uses a two-stage, center-mountedscrew to deal with watery muck. One screw conveyor will run faster than theother, creating a muck plug that will push water out of the screw conveyor. Themachine’s mixed ground cutterhead is fitted with interchangeable knife bits anddisc cutters. In addition, the cutterhead is clad with extensive wear platesfor abrasion protection. The mixing chamber can be filled with water, foam andother additives to keep it spark-safe in the presence of methane.
“The machine essentially uses its EPB technology to dealwith methane gas safely,” said Doug Harding, Robbins Vice President. If any methane leakage is detected, anevacuation system called a “snuffing box” will draw methane out of the end ofthe screw conveyor and directly into the ventilation system. “The TBM tunnelingmethod will deliver advances in safety, higher quality drifts, and fasterproject development,” said Tonkin.
A final unique aspect of the project is a specially-designed“Quick Removal System”. As noground in Australia can be left unsupported and the machine is boring a blindtunnel, it will be able to retract in one piece from its shield, leaving the shieldin place. “The core of the machine is a bolted design that separates from theshield, in a process that does not require a cutting torch,” said Harding. The TBMcore and back-up will then be walked up the decline tunnel on a set of customtransport dollies and moved to the second decline tunnel, where another set ofshields will be waiting for machine assembly prior to launch.
This article was provided by TheRobbins Co.