Stability analysis of yield-support composite coal pillars in rockbust-prone mines

GUO Zhengjun; SHI Qingwen; LIU Jie; SUN Jintao; CHENG Yikun; QIN Hongyan; HAN Zhe; WANG Jiayang; HU Chaowang; HONG Aokun; WANG Xinshaung; WANG Xiangyu; LI Jianzhong; SHI Yao

doi:10.19956/j.cnki.ncist.2026.01.021

Abstract：A yield-support composite coal pillar system integrates both narrow and wide pillars.It functions by combining mechanisms of yieldable ground release and stable support to prevent impact-induced instability(Coal burst)in coal pillars.This study is based on the boundary coal pillars of a 290 m wide extraction area located in an outburst-prone mine in Ordos.It designs a"yield-support" combined scheme based on limit e-quilibrium theory and employs the finite element method to simulate the stress evolution and failure process un-der the mining-induced activities of the adjacent longwall face,clarifying the typical stress concentration areas during mining.The results indicate significant high-stress concentrations throughout the entire yield pillar and within a 20-meter zone of the adjacent supporting pillar,as well as in a 50-meter zone on the side of the sup-porting pillar farthest from the yield pillar.In contrast,an approximately 136m-wide area inside the supporting pillar constitutes a low-stress zone.At a mining depth of 750m,the critical width for the yield pillar is deter-mined to be 33.7 m;the currently designed yield pillar satisfies this stability requirement.Dynamic simulation further elucidates the mechanical behavior of the composite structure:a 40 m wide yield coal pillar effectively dissipates the deformation energy of the overlying strata through extensive plastic deformation,redirecting stress toward the two adjacent bearing coal pillars.This ultimately results in an asymmetric stress field,where the stress peak and plastic zone depth on the goaf side of the bearing coal pillars are significantly greater than those on the solid coal side.The core engineering value of this study lies in replacing traditional single coal pillar designs with yield-bearing composite coal pillars in deep rock burst-prone mines to more effectively mitigate rock burst impacts.Based on the stress distribution results,key anti-rock burst prevention zones are clearly delineated.In practical engineering applications,targeted reinforcement support or pressure relief measures can be implemented in these areas,thereby achieving scientific and precise prevention and control.The research findings provide valuable insights for the design of"yield-bearing" composite coal pillars in deep rock burst- prone mines in China.