An innovative approach for gob-side entry retaining in highly gassy fully-mechanized longwall top-coal caving

Abstract An innovative gateroad layout in highly gassy longwall top coal caving in a Chinese coal mine based on gob-side entry retaining (GER) was introduced. The numerical model was used to design the rational roadside backfill body (RBB) with high-water quick-setting materials. In order to improve the reliability of the numerical modeling, the double-yield model for gob modeling and the strain-softening model for RBB modeling are validated in detail. The results of the validated model indicate that when the RBB width is 1.5 m, the RBB peak vertical stress is minimal and surrounding rock convergence variation of GER becomes gentle. Consequently, the rational RBB width can be estimated as 1.5 m. Field test and field monitoring indicate that the GER in N2105 panel with a width of 1.5 m roadside backfill body and high-strength cable-rockbolt support could meet the requirement for gas drainage and ventilation during panel N2105 was retreating. It also proved that the new gateroad layout met the requirement for the highly gassy thick seam operation, and provided a new way to the coal mine safety production in similar conditions.