NIU H P, PAN R K, YU W D,et al. Mechanical characteristics of coal pillars in complex-structure coal seams and optimization of roadway surrounding rock stability[J].Journal of Henan Polytechnic University(Natural Science) ,2025,44(6):118-126.

doi:10.16186/j.cnki.1673-9787.2025010009

Received: 2025/01/06

Revised: 2025/06/17

Published: 2025/10/14

Mechanical characteristics of coal pillars in complex-structure coal seams and optimization of roadway surrounding rock stability

Niu Haiping1, Pan Ruikai1, Yu Weidong1, Shen Yuxu1,2, Wu Shaokang3

1.Department of Mining Engineering， Shanxi University of Energy， Jinzhong  030600， Shanxi， China；2.Ministry of Education Laboratory of Insitu Modified Mining， Taiyuan University of Technology， Taiyuan  030244， Shanxi， China；3.School of Energy and Mining， China University of Mining and Technology （Beijing）， Beijing  100083， China

Abstract: Objectives To address the problems of severe roadway surrounding damage and poor stability during mining of complex-structure coal seams， the failure mechanism of coal pillars under roadway stress was investigated， taking the 10103 face of Baozigou Coal Mine as a case study. Methods Field measurement， mechanical analysis， numerical simulation， and field tests were employed to investigate the mechanical characteristics of coal pillars in complex-structure coal seams and to develop optimization strategies for roadway surrounding rock stability.  Results A theoretical calculation formula for coal pillar size in complex-structure coal seams was derived， and the optimum roadway-protective coal pillar width was determined to be 5.66~7.04 m. It was revealed that the plastic zone depth of coal pillars under mining influence is 2.8 times that of conventional coal seams， confirming the regulatory effect of interlayers on the stress redistribution process of surrounding rock. The evolution laws of vertical stress， vertical displacement， horizontal stress， and horizontal displacement were clarified， and a coal pillar width of 7 m was found to effectively enhance roadway surrounding rock stability， verifying the theoretical results. Field application of the optimum pillar size showed remarkable improvement in roadway conditions before and after implementation.  Conclusions Increasing coal pillar width enhances bearing capacity， but excessive width leads to stress concentration on the goaf side， endangering overall stability. The results provide significant guidance for the rational design and application of coal pillars in complex-structure coal seam mining， offering new theoretical and practical references for the field.

Key words: complex-structure coal seam; coal pillar size; mechanical model; stress evolution law; surrounding rock stability