Influence of coal rib pillar width on the stability of strata around the face-end and gatehead in longwall mining

CIM Bulletin, Vol. 74, No. 830, 1981

TONY B. SZWILSKI, Associate Professor, Mining Engineering, University of Kentucky, Lexington, Kentucky

The efficiency of operation and life of an advancing longwall coalface depends, to a great extent, on the face-end roof strata conditions and the stability of the gateroads. The factors that influence the rate of closure of gateroads are examined, in particular the gateside pack and the coal rib (crush) pillars. The performance of mechanized packing systems is briefly discussed. Gateroad deformation surveys were carried out at two coal mines to determine the influence of the rib pillar width on gateroad stability; also, the influence of the gateside pack on the immediate roof and floor strata is analyzed based on strata bed displacement measurements from instruments installed in the gateroad and pack-hole of a longwall advancing face operating in a thick seam (7.55 m). Concluding, an evaluation of the face-end systems examined is given and recommendations made for the most suitable rib pillar width, face-end geometry and roof strata reinforcement.
Keywords: Coal mining, Pillars, Rib pillars, Ground control, Longwall mining, Gateroads, Packing systems, Roof control.