Document Type

Conference Paper

Publication Date


Publication Details

This conference paper was originally published as Shen, B, Poulsen, B, Kelly, M, Nemcik, J & Hanson, C, Roadway Span Stability in Thick Seam Mining - FIeld Monitoring and Numerical Investigation at Moranbah North Mine, in Aziz, N (ed), Coal 2003: Coal Operators' Conference, University of Wollongong & the Australasian Institute of Mining and Metallurgy, 2003, 173-184.


Comprehensive field monitoring and numerical analyses of roadway span behavior have been conducted at Moranbah North Mine as part of an ACARP Project for Rapid Roadway Development. The response of the coal roof to roadway development in a 5.5m thick seam was studied. The monitoring program was highlighted by successfully measuring the roof stress change prior to, during and after the roadway excavation. Roof displacement was also monitored after the installation of roof support. Measured in situ stresses in the coal seam were much lower than estimated from the overburden depth. The monitored vertical stress in the coal roof exhibited a rapid drop immediately after the roadway face passed the monitored locations. It however, recovered substantially (up to 50%) in the next 10 hours. Two roadway sections 60m apart were monitored. The monitored roof displacements and stresses in the two locations showed a significant difference. The sites were separated by two normal faults. The monitored roadways were simulated using fully coupled mechanical-flow models. The numerical results suggested that the drainage of gas/water around the roadways was likely to be the main cause of the observed stress recovery in the coal roof. It was also found that the presence of high gas/water pressure in the coal seam would result in lower stress readings with the stress measurement technique. The measured stress is close to but not necessarily equal to the effective stress.