Abstract：The variations in shear force induced by the orebody dip angle significantly affect the bearing capacity of pillars. To investigate the bearing characteristics and failure modes of pillars under different dip angles, a series of “roof-inclined pillar-floor” loading tests were designed and conducted. Acoustic emission (AE) monitoring was employed to capture real-time crack evolution signals, while an adaptive denoising algorithm, based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and permutation entropy (PE), was applied to enhance the signal-to-noise ratio and reliability of the AE signals. By combining AE response characteristics with parameter sensitivity analysis, the mechanism by which the dip angle affects the bearing characteristics and failure modes of the specimens was investigated. The results indicate that the dip angle significantly reduces the bearing capacity of the pillars. As the dip angle increased from 0° to 15°, the average bearing capacities of the three pillar aspect ratios (0.8, 1.0, and 1.5) decreased by 4.28%, 6.49%, and 14.84%, respectively. Furthermore, the higher the aspect ratio, the greater the sensitivity of the bearing capacity to the dip angle. The CEEMDAN-PE adaptive denoising algorithm improved the signal-to-noise ratio by 7.86 dB compared with conventional wavelet denoising, effectively preserving microcrack signals. AF (average frequency)-RA (rise angle) parameter analysis revealed that the proportion of shear failure increased by 4.4%, 3.8%, and 10.4% for the three aspect ratios compared to the 0° dip angle. Both the cumulative ringdown count and cumulative energy increased significantly, with average increases of 145.9% and 90.06%, respectively. These findings reveal that as the dip angle increases, the damage severity of the “roof-inclined pillar-floor” system intensifies, with the failure mode evolving from tension-dominated to combined tensile–shear failure. At 15°, shear failure along a single inclined plane became dominant. Moreover, as the aspect ratio increases, the failure mode becomes increasingly sensitive to the dip angle. These results provide an experimental foundation for the stability assessment of inclined pillars in hard-rock.
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2026, Vol. 45 
