• Williams, D. J.
• Erarslan, N.
• Qin, Johnny
• Shen, Baotang

Abstract

Coal and associated coal measure rocks including shales, mudstones and sandstones may lose significant strength with water saturation due to the absorption of water, stress corrosion or mineralogy change of clays within the rock matrix. As most coal seams are natural aquifers water ingress into underground mine workings is common and typically controlled during mining by dewatering pumps. With mine closure, unless ongoing pumping is maintained, workings will flood and coal pillars and pillar roof and floor foundations will revert to fully saturated conditions. In physical testing of coal and coal measure rocks at insitu and saturated water contents this reduction in strength is quantified. From this and the distribution of stone in a logged coal pillar from Queensland, Australia the strength reduction of a coal pillar with water saturation is estimated by numerical methods. It was found that the modelled pillar strength reduction could be estimated by weighting the strength reduction of the pillar component lithological units by the relative quantity of each unit.

Topics

• impedance spectroscopy
• strength
• stress corrosion