The Control Mechanism of the Coal Pillar Width on the Mechanical State of Hard Roofs

Qifeng Jia, Songtao Ji (), Jie Zhang, Zhiyu Fang, Chao Lyu and Jurij Karlovšek
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Qifeng Jia: College of Energy and Mining Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
Songtao Ji: College of Energy and Mining Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
Jie Zhang: College of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
Zhiyu Fang: College of Energy and Mining Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
Chao Lyu: College of Energy and Mining Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
Jurij Karlovšek: School of Civil Engineering, The University of Queensland, Brisbane, QLD 4067, Australia

Mathematics, 2025, vol. 13, issue 16, 1-21

Abstract: This study addresses the critical challenge of optimizing coal pillar width in burst-prone mines with thick, hard roof strata, balancing resource recovery, roadway stability, and coal burst mitigation. Through integrated analytical modeling and rigorously calibrated numerical simulations, the research reveals the complex interplay between pillar width, roof mechanics, and stress redistribution. Key findings demonstrate that pillar width dictates roof failure mechanics and energy accumulation. The case study indicates that increasing the coal pillar width from 6 m to 20 m shifts the tensile fracture location from solid coal toward the pillar center, migrates shear failure zones closer to roadways, and relocates elastic strain energy accumulation to the pillar area. This concentrates static and dynamic loads directly onto wider pillars upon roof fracture, escalating instability risks. A risky coal pillar width is identified as 10–20 m, where pillars develop severe lateral abutment pressures perilously close to roadways, combining high elastic energy storage with exposure to roof fracture dynamics. Conversely, narrow pillars exhibit low stress concentrations and limited energy storage due to plastic deformation, reducing burst potential despite requiring robust asymmetric support. Strategic selection of narrow or wide pillars provides a safer pathway. The validated analytical–numerical framework offers a scientifically grounded methodology for pillar design under hard roof conditions, enhancing resource recovery while mitigating coal burst risks.

Keywords: coal pillar width; hard roof; ground control; abutment stress; numerical simulation (search for similar items in EconPapers)
JEL-codes: C (search for similar items in EconPapers)
Date: 2025
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