AbstractThe observations developed in this paper are intended to provide researchers and mining engineers with initial estimate of the burst risk of coal pillar, as the study of bursting liability is of importance in forecasting and preventing the bump of coal pillar. Bursting Energy Index (WCF) is selected in this study to describe the influence of roadway backfill on bursting liability and strength of coal pillar. For the general study undertaken in this paper, a formula derived from the combined South African and Australian databases was used to analyze the bursting liability of coal pillar. Based on over 60 numerical models of various pillar height and backfill percentage, a series of average axial stress-strain curve of 5∼10m coal pillar with roadway backfill is attained. Modelling results suggest that the pillar strength will increase with increasing roadway backfill. It also can be seen that the Bursting Energy Index (WCF) will decrease with increasing roadway backfill while the percentage of decrease amount of WCF will increase versus the percentage of roadway backfill. The increase in pillar strength is greater for the tall pillars than squat pillars. It is also observed that the central portion of coal pillar defined as elastic pillar core plays a significant role on loading capacity of pillars, increasing coal pillar strength and decreasing Bursting Energy Index (WCF).