Abstract:According to the mining conditions, three combination models of surrounding rock and backfilling body stope sizes were designed. The fracture evolution of the combination under triaxial loading was monitored by using biaxial testing machine, pseudo triaxial device, and acoustic emission system, and the acoustic emission characteristics of the combination fracture process were studied. The results show that the AE event rate and AE energy are in the "quiet period" before the plastic stage, and there is a sudden increase in the plastic stage, which can be used as a macroscopic fracture early warning near the stress peak; AE event rate peak and AE energy peak are delayed with the increase of side pressure, and the stability of the combination gradually enhances with the increase of side pressure. AE event rate peak and AE energy peak are opposite with the increase of size; AE energy peak increases with the increase of side pressure and decreases with the increase of size. The sudden increment of AE energy in the early warning stage decreases gradually with the increase of side pressure and increases gradually with the increase of size; Kaiser effect appears in the range of 70%~85% of the peak stress of the combination, and the Kaiser effect point has a certain early warning effect on the macroscopic fracture of the combination in the plastic stage. The research results are expected to provide a reference for the study of the interaction mechanism between backfill and surrounding rock.