Paper contribution

Computer-Aided Selection of Pillar Geometry in Deep Room-and-Pillar Panels Using Calibrated Large-Scale 3D FEM

Krzysztof Fulawka; Piotr Mertuszka; Lech Stolecki; Mateusz Malesza; Radoslaw Wasilewski

Proceedings
EUROCK 2026
Pages
845-850
Submitted
28 January 2026
Accepted
15 June 2026
Published
12 August 2026

Summary

Abstract

Room-and-pillar mining at great depth must balance two competing targets: keeping the roof–pillar system stable under high in-situ stresses while maintaining high extraction. In panels affected by stress redistribution from nearby mined-out areas, empirical rules and simplified models may miss full-scale interactions and local damage, which can lead to sub-optimal design choices. To support variant selection, a full-scale 3D finite element model was developed for a high-risk panel in the Rudna copper mine (Poland). The model domain (1.5 × 1.5 × 1.0 km) was implemented in GTS NX and used the Generalized Hoek–Brown failure criterion with GSI-based rock mass reduction. Mining-induced degradation was represented by assigning different parameter sets to key geomechanical zones (intact rock mass, large protective pillars, technological pillars, and mined-out/backfilled areas). The model was iteratively calibrated against in-situ convergence measurements from multiple monitoring locations to obtain a realistic deformation response. Three room-and-pillar layouts were analysed with staged excavation reflecting mining advance and the liquidation phase with 4×3 m remnant pillars. The tested pillar geometries were 4×4 m, 5×6 m, and 8×8 m. The simulations showed clear differences in stability factor distribution and roof deflection behaviour. The 4×4 m variant produced unstable zones (FS < 1). The 8×8 m variant achieved the highest recovery (~93%), but it also indicated a stiff response and rapid loss of load-bearing capacity during pillar cutting, which may increase the likelihood of dynamic roof behaviour and elevated seismic risk. The 5×6 m variant offered the most balanced outcome, with acceptable stability (FS ≈ 1.1), high recovery (~90%), and a more controlled roof deflection process. These results show that a calibrated full-scale 3D FEM model can be used as a practical decision tool to compare deep room-and-pillar variants, quantify safety margins, and select layouts that maximise recovery without compromising stability.

Contributors

Authors

  1. Krzysztof Fulawka KGHM CUPRUM Sp. z o.o. – Centrum Badawczo-Rozwojowe, Poland ORCID 0000-0002-0534-0712
  2. Piotr Mertuszka KGHM CUPRUM Sp. z o.o. – Centrum Badawczo-Rozwojowe, Poland
  3. Lech Stolecki KGHM CUPRUM Sp. z o.o. – Centrum Badawczo-Rozwojowe, Poland
  4. Mateusz Malesza KGHM Polska Miedź S.A, „Rudna Mine”, Polkowice, Poland
  5. Radoslaw Wasilewski KGHM Polska Miedź S.A, „Rudna Mine”, Polkowice, Poland

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References

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