Laboratory study on the propagation of edge cracks in rock-like material and its implication in coal mining

Rock fracture propagation is a major hazard for mining and tunnel excavation in fractured rock masses or coal seams. A longwall panel with typical dimension of 200m (width)×1000m (length)×3m (height) can be considered as an open edge crack. The fracturing processes the vicinity crack (or panel) particularly roof floor are critically important safety operation because lead to water inrush dynamic loading on working face. It’s therefore understand predict pre-existing initiation masses. This paper describes study investigating mechanisms pathways under uniaxial compression. In this study, rock-like material which consists model gypsum, diatomaceous earth at mass ratio 165:75:2 was used. compression strength decreased increase length During tests, wing (tensile) cracks were first observed tip followed by secondary increased. final failure specimens however dominated tensile throughout specimens. Due sudden initiations specimens, stress specimen varies stepwise, acoustic emission (AE) energy amplitude showed abrupt changes when initiated. When occurred, notable retreat stress-strain curve, recorded AE sharp spike. These findings from experimental have been applied underground explain panel. process associated resembles formation flow channels during mining.