Abstract:The upper and lower iron ore layers in Gongchangling Iron Mine are apart only by 10m. The upper ore layer is first extracted and backfilled before the lower layer is mined. Due to the short upright interval, a large mined out area in the lower layer may affect the ground stability of the upper layer, posing a risk of falling interval rock pillars and backfilled material in the upper layer. A study was therefore conducted based on the mining design and the stope structural parameters, through the finite difference method. The study shows that when the upper layer is mined without backfilling, connections will form in the plastic zones of the interval rock pillars between the upper and lower layers, with tensile stress approximating 1MPa; when the mined areas of the upper layer are timely backfilled, however, no connections form in the plastic zones, with rather low tensile stress, and both the rock pillars and the stopes can remain stable.
