• Multi-source dynamic disturbances and unloading damage synergistically accelerate strength degradation in pre-damaged granite, with reductions up to 16.7%.
• Shear-slip failure preferentially occurs along blast-induced fractures, and layered failure on free surfaces indicates disturbance-induced fracture localization.
• Critical precursor frequency bands (105–150, 185–225, 300–325 kHz) serve as diagnostic signatures for impending rockburst.
• A grouting-based wave-absorption strategy effectively mitigates deep dynamic disasters by attenuating disturbance amplitude and reducing excitation frequency.