Paper contribution

Analysis of Underground Roadway Stability under Geomechanical Parameters Uncertainty using RS2 Finite Element Modelling

Martin Itoolwa Kulula; Piotr Małkowski

Proceedings
EUROCK 2026
Pages
751-756
Submitted
28 January 2026
Accepted
15 June 2026
Published
12 August 2026

Summary

Abstract

Underground roadway stability is still often assessed using a single deterministic set of rock mass inputs, which can mask the influence of natural variability in stiffness and strength. This study quantifies the effect of uncertainty in Young’s modulus (E) and uniaxial compressive strength (UCS) on roadway performance using RS2 finite-element modelling. Laboratory testing of core specimens from an underground mine provided E and UCS datasets for three lithological units: claystones, siltstones, and sandstones, which were used to define input distributions. UCS was modelled as normally distributed for all lithologies, while E was normal for claystone and siltstone and lognormal for sandstone to reflect observed skewness and non-negativity. Three complementary scenarios were analysed: (1) a deterministic Base case using laboratory mean E and UCS, (2) an ensemble mean response (μ) from 200 Latin Hypercube realisations per lithology, and (3) a statistical condition (μ−0.5σ) reported by RS2 Interpret. Outputs focused on crown vertical displacement and roof strength factor (SF), extracted along a standardised offset query line to ensure consistent comparisons. Results show that uncertainty effects concentrate in the weakest unit: the claystone-dominated lithology governs convergence demand and stability margin, with crown convergence reaching 28.6 mm and SFmin dropping to 0.96 under μ−0.5σ. Siltstone and sandstone exhibit lower convergence and generally higher SF, providing consistency checks. Combining μ and μ−0.5σ offers a practical screening basis for separating expected performance from a less favourable statistical condition in variable ground.

Contributors

Authors

  1. Martin Itoolwa Kulula AGH University of Krakow, Poland ORCID 0000-0003-0870-438X
  2. Piotr Małkowski AGH University of Krakow, Poland ORCID 0009-0008-0843-7174

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