## 4 Discussion  
Rockbursts are nonlinear, sudden, and complex geological events that can be better understood by dividing their progression into distinct periods. This phased approach allows for a systematic analysis of the characteristics and underlying mechanisms at each period. Moreover, as acoustic emission activity varies significantly across the different periods, identifying these patterns allows for more accurate real-time monitoring and early warnings. This is especially crucial during the critical prepeak intensive period and the rockburst period, where timely detection is essential for ensuring workplace safety. From Figure 6a, which illustrates the amplitude-frequency distribution of acoustic emissions, it can be observed that granite specimens AG2 and AG3 exhibit a strong linear relationship. The correlation coefficients R\({}^{2}\) are 0.9527 and 0.9195, respectively, both exceeding 0.9, which aligns well with the Gutenberg-Richter (G-R) relationship. Furthermore, from an analysis of the variations in AE counts and \(b\)-values during the strain-mode rockburst tests (illustrated in Figure 6b), the following findings can be made:  
1. The acoustic emission signals reflect the generation, propagation, and coalescence of microcracks within a rock mass, revealing the progressive stages of its failure. Based on the intensity of acoustic emission activity, the experimental process can typically be divided into four phases: the initial intensive period, the quiet period, the prepeak intensive period, and the rockburst period. 2. Initial intensive period. In the initial stage of loading (primarily within the first 0 to 180 s), the primary cracks and pores within the rock sample undergo compaction and closure under external pressure. This process causes friction along fracture surfaces, releases elastic energy, and generates frequent acoustic emission signals. While the AE count shows concentrated activity, the overall intensity remains relatively low. Meanwhile, there is a slight decline observed in the AE \(b\)-value. 3. Quiet period. As loading continues, the granite specimen primarily undergoes elastic deformation under external stress. During this stage, the formation of internal fractures slows down significantly, resulting in a noticeable reduction in acoustic emission activity. This creates a relatively quiet period, when the AE counts are infrequent and occur at low levels. The acoustic emission characteristics observed during this period are evident in various rockburst experiments and field monitoring [29; 30; 31], gaining widespread recognition. This phase, marked by its extended duration, can serve as a precursor indicator of rockbursts. Notably, the \(b\)-value of acoustic emissions tends to rise, signaling a shift in the rock's internal stress state. 4. Prepeak intensive period. As the rock mass approaches its ultimate bearing capacity, plastic deformation within the rock sample gradually becomes dominant. The macroscopic cracks that are formed as microfractures and voids inside the rock evolve, close, and eventually interconnect. This process generates a significant surge in acoustic emissions, with a dense clustering of AE counts. During this phase, the AE counts demonstrate a pronounced trend of intensive growth, serving as a potential precursor to an imminent rockburst. Concurrently, the AE \(b\)-value drops significantly, signaling the rock's nearing failure, and the characteristics are found to be completely consistent with the \(b\)-value observed prior to the occurrence of a rockburst in the Sanhejian Coal Mine [32]. 5. Rockburst period. When the rock mass reaches its ultimate failure threshold, the stored internal energy is released abruptly, causing rapid propagation of fractures that coalesce into through-going failures, ultimately triggering a rockburst. At this moment, AE counts reach their peak, accompanied by an exceptionally dense signal pattern. As the rockburst subsides, AE activity gradually diminishes.