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Geomechanics and Engineering
  Volume 28, Number 5, March10 2022 , pages 463-475

Post-pillars design for safe exploitation at Trepça hard rock mine (Kosovo) based on numerical modeling
Gzim Ibishi, Melih Geniş and Mahmut Yavuz

    In the mine exploitation stage; one of the critical issues is the stability assessment of post-pillars. The instability of post-pillars leads to serious safety hazards in mining operations. The focus of this study is to assess the stability of post-pillars in the 130# stope in the central ore body at Trepça hard rock mine by employing both conventional (i.e., critical span curve) and numerical methods (i.e., FLAC3D). Moreover, a new numerical based index (i.e., Pillar Yield Ratio-PYR) was proposed. The aim of PYR index is to determine a border line between stable, potentially unstable, and failure state of post-pillars at a specific mine site. The critical value of pillar width to height ratio is 2.5 for deep production stopes (e.g., > 800 m). Results showed that pillar size, mining height and mining depth significantly have affected the post-pillar stability. The reliability of numerical based index (i.e., PYR) is verified based on empirical underground pillar stability graph developed by Lunder, 1994. The proposed pillar yield ratio index and pillar stability graph can be used as a design tool in new mining areas at Trepça hard rock mine and for other situations with similar geotechnical conditions.
Key Words
    FLAC3D software; hard rock mine post-pillar design; underground excavation
Gzim Ibishi: Department of Mining Engineering, Faculty of Geosciences,
Mitrovica Isa Boletini University, 40000, Mitrovica, Kosovo
Melih Geniş : Department of Mining Engineering, Faculty of Engineering,
Zonguldak Bülent Ecevit University, 67100, Zonguldak, Turkey
Mahmut Yavuz: Department of Mining Engineering, Faculty of Architecture and Engineering,
Eskişehir Osmangazi University, 26040, Eskişehir, Turkey

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