Estimation of Applied Stresses on Pillars in Stope and Rib Pillar mining Method by Numerical and Empirical Methods in Fetr 6 Chromite Mine

Fetr6 is one of the Iran’s underground mines in which chromite had been extracted with room and pillar mining method. In Phase 1 of this mine، after the occurrence of a large scale failure، mining operations ceased and the stope and rib pillars mining method with delayed backfill was designed for phase 2. To design pillars in this method، it was necessary to understand the values of applied stress on pillars. Therefore، widespread and thorough studies were carried out to obtain them for this research. The values of applied stresses on pillars were estimated by numerical and empirical methods. Also، the effects of depth and sequence of ore extraction were investigated using both methods more precisely. The results show that while the plastic zone is not created in pillars، the estimated values by empirical methods are maximum 35% more than the real values and pillar position in the layout of mine is an important parameter on its stress values. But there are not meaningful differences between two methods when plastic zone is created in pillars.