Document Type

Conference Paper

Publication Date

2002

Publication Details

This conference paper was originally published as Seedsman, R, Brisbane, P & Mitchell, G, Strata Management at the Goonyella Exploration Adit Project, in Aziz, N (ed), Coal 2002: Coal Operators' Conference, University of Wollongong & the Australasian Institute of Mining and Metallurgy, 2002, 193-202.

Abstract

The Goonyella Exploration Adit is a three heading development into the highwall at Ramp 4 at Goonyella Riverside Mine that was driven between September 1999 and November 2000. The principal was BHP Billiton Mitsubishi Alliance (BMA) and the contractor was Allied Mining Australia. Strata management began at the pre-tender phase and evolved as greater knowledge of the ground became available. Roadways were driven 3.6m high, 5m wide in the 7m – 8m thick Middle Goonyella Seam. The cut and flit mining system was used with extended cuts of 12m to 15m and a minimum support pattern of 4 x 1.5m tensioned bolts at 1.5m centres. Extended cuts were possible, even at the maximum depth (290m), so long as an adequate thickness of massive top coal was left. Horizon control was the basic strata management tool in the project. Extensive exploration using both drilling and 3-D seismic methods was available and proved to be reliable in detecting faults greater than 3m throw. Systems to identify the proximity to thrust faults during driveage were successful in identifying smaller scale thrust faults. Small-scale normal faults striking parallel to the roadways were encountered, typically in only one of the three headings, and these impacted substantially on the mining rates. They were not detectable from any exploration program. The term trench roof was adopted to describe the associated roof falls – less than 2m wide, up to 1.5m high and bounded by fault or joint planes. The falls were interpreted as being vertical drop-outs from a coal roof under very low horizontal confinement.

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