Axial compression tests with lateral confinement conditions were conducted to investigate the deformation and energy dissipation of broken rock masses with varying Talbol gradation indices (n = 0.2-1.0) in a goaf's collapse zone, with real-time energy release monitored via acoustic emission (AE) technology. The compaction process occurs in three stages: initial, linear, and plastic consolidation. The void fraction decreases nonlinearly with stress, with a larger gradation index resulting in a higher initial void fraction but a smaller final reduction. After compaction, the fractal dimension of the samples increased significantly (ΔD = 0.1059-0.7946), narrowing the range from 2.0-2.8 to 2.7946-2.9059, demonstrating a homogenization effect. The evolution of AE energy is closely coupled to the compaction phases. The initial stage is dominated by low-energy, high-frequency signals, while later stages feature high-energy, low-frequency events from particle breakage. An increase in gradation index leads to a decrease in cumulative AE counts but a significant increase in the energy of individual events, revealing distinct energy release modes.
Peiyun et al. (Thu,) studied this question.