Abstract: To study the influence of mining reserved pillar on backfill body stability，a mining size scheme of 180 m×15 m×20 m (strike length × height ×width) for ore pillars is proposed by using a pillar design method by considering confinement factor and combining ore rock occurrence conditions in one gold mine.The mining of pillar between 590 and 605 mRL is numerically analyzed by using MAP3D software.The results indicate that the upper backfill body still keeps stable when the pillar is mined out in normal primary rock stress，and in worse primary rock stress，large portion of the upper backfill body is predicted to be in tension which means it may occur unstable failure.The empirical pillar design formula is modified by using limit equilibrium equation and the requirement of reducing the backfill body′s uniaxial compressive strength by reducing the stope span and strengthening supporting is put forward.This research conclusion can ensure the safety of mining out the reserved pillar and the stability of the upper backfill body.It also can provide design ideas for other similar mines.

Key words: Reserved pillar, Backfill body, Numerical simulation, Stability