Pillar recovery safety evaluation based on stress increment theory

Pillars are main support units of goaf stability.The recovery of the pillars will cause stress redistribution and stability of the goaf.The pillaring process security is analyzed based on stresses incremental theory.The numerical model is established according to the order of pillar recovery.The stress of each pillar before and after mining are calculated,the results show that all factors of pillars safety are greater than 1,that is,all the pillars are in a safe state.