1457 deflection. The model geometry and stratigraphy were built based on available exploration and mine geological data in the vicinity of the panel. The numerical domain was set to approximately 1.5 × 1.5 × 1.0 km to properly capture far-field stiffness contrasts and boundary effects influencing the mining horizon. Three mining-layout scenarios were analysed, differing in the geometry of technological pillars (4×4 m, 5×6 m, 8×8 m). In all scenarios, remnant pillars in the liquidation/goaf zone were kept consistent (4×3 m) to ensure comparability between variants. Figure 3 - Considered exploitation scenarios with marked stages of mining front line Discretization was performed using a hybrid mesh (tetrahedral + hexahedral elements) with mesh grading. The maximum element size at the mining level was about 1.5 m, while in strata distant from the excavation horizon the mesh was progressively coarsened (up to ~35 m) to optimize computational cost while preserving accuracy in the area of interest. Figure 4 - View of lithological strata represented in the 3D numerical model (left) and Hybrid discretization of the large-scale 3D numerical model (right) Rock mass behaviour was represented using the Generalized Hoek–Brown (GHB) strength criterion
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