Compressive properties analysis of mono-sized fragmented coal and rock.

The compressive properties of fragmented coal and rock aggregates within goaf critically influences surface subsidence dynamics and reservoir development strategies. This study conducted constrained compression testing on mono-sized fragmented coal and rock particulate materials using a custom-designed compaction apparatus, evaluating parameters including compressive resistance, pre-/post-compaction mass variations, porosity evolution, and acoustic emission (AE) signatures. Experimental observations demonstrated progressive yet decelerating axial strain development under increasing stress, accompanied by diminishing porosity reduction rates. AE activity exhibited proportional escalation in both event frequency and energy release intensity during particle consolidation. Particle dimension inversely correlated with compaction strength, while fragmented coal generated higher AE responses compared to rock counterparts. Three distinct compression phases were identified: void compaction, pore compaction, and particle recombination. These findings establish mechanistic insights for optimizing goaf flow field modeling and backfill mining techniques through enhanced understanding of energy dissipation patterns in particulate media.