Stress distribution on longwall barrier pillar due to goaf formation during extraction

Abstract

Mechanised longwall mining is a sustainable option to achieve higher production from underground coal seams. Judicious design of underground longwall panel requires understanding of stress distribution on barrier pillars during different stages of extraction. The paper presents a study of stress distribution in and around barrier pillars for the condition wherein extraction in both the adjacent panels are completed and goaf exists on either side of the pillar. Finite element analysis was taken up for parametric study of varying widths of barrier pillar and different degrees of compaction of broken material in the goaf formed during extraction. Analysis revealed that the stress transferred on pillar decreased as the width of barrier pillar increased. Stress intensity at pillar edges was higher than that at centre of the pillar. Stress distribution in the strata lying above barrier pillar was influenced considerably by the compaction of goaf material.