Mining induced stresses

Mining operations cause the stress to concentrate at the corners of the solid coal, the edges of the workings and at the pillars. Room and pillar mining is more prone to outburst than longwall mining due to the stresses inherent in the pillars. However, the removal of support pillars is nearly always completely safe as the gas has diffused from the pillars over time. As stresses concentrate at the ends of longwall faces, longwall mining should use a straight working face, complete extraction of the coal and rapid stowing.(Lama & Bodziony, 1996)