Stability analysis and engineering implications of lateral mining-induced narrow coal pillars under double-roadway layout in deep mines

• UDEC-Trigon model calibrated collapse behavior and coal pillar stability. • Lateral mining produces a double-peak stress pattern with rib coefficients of 2.1–2.7. • A 6 m pillar provides optimal stability, while a 4 m pillar deforms excessively. The narrow coal pillar double-roadway layout has emerged as a key strategy for enhancing resource recovery in deep shaft mines. Using representative engineering conditions from western China, this study develops a refined numerical simulation framework based on the UDEC-Trigon discrete element method to reproduce roof collapse behavior and evaluate coal pillar stability with high fidelity. The framework integrates a fracture-controlled calibration procedure and explicitly captures the progressive failure mechanisms governing pillar behavior under deep mining conditions. Simulation results indicate that coal pillars with widths of 4, 6, 8, 10, and 12 m exhibit a distinct double-peak vertical stress distribution during lateral mining. The stress concentration coefficient on the solid coal rib remains within 2.1–2.7 across all cases, and overall stress optimization improves as pillar width decreases. However, while the 4 m pillar experiences relatively lower stress concentration, its excessive deformation exceeds allowable limits, compromising the serviceability of the adjacent roadway. In contrast, the 6 m pillar achieves the most favorable balance between deformation control and structural stability. This study quantitatively determines the optimal width of narrow pillars and elucidates the governing stress-failure mechanisms under double-roadway layout. The proposed framework and findings provide a practical basis for roadway layout optimization, contributing to safer roadway construction, improved pillar design, and enhanced resource recovery in deep coal mines. Stability Analysis and Engineering Implications of Lateral Mining-Induced Narrow Coal Pillars under Double-Roadway Layout in Deep Mines