A Coal Pillar Burst Assessment Index Based on Numerical and Analytical Tools

Coal bursts are challenging to predict due to their highly complex and dynamic nature. In recent years, efforts to integrate established indices, such as Burst Potential Index (BPI), Energy Storage Rate (ESR), and Strain Energy Density (SED), with numerical computation modeling have shown potential. This study aims to develop a novel burst risk assessment tool for individual coal pillars in a longwall gate-road system (LGS). A modified pillar-specific BPI (mBPI) is proposed and couples analytical indices with numerical modeling. The modified index expands the classic BPI by removing the limitations stemming from considering only the elastic region of the material constitutive model and the stress-strain behavior under uniaxial loading. The effect of various geometrical and geomechanical parameters on the mBPI is evaluated through a parametric analysis. A total of 47 numerical models were generated to calculate the mBPI of an LGS pillar for different conditions. The results indicate that coal strength and coal stiffness, in-situ horizontal stresses, overburden depth, and pillar width have a substantial effect on the mBPI, while the width of the LGS yield pillar has a minimal impact on the mBPI.