Abstract: The rockburst experiments were conducted on red coarse-grain granites with different water saturations by using true triaxial rockburst test system. Then this study analyzed the characteristics of strength and deformation, damage and ejection process, failure mode and acoustic emission (AE) of rock specimens after rockburst with different water saturations. The relationship between the water saturation and kinetic energy of rockburst ejection and the influence mechanism of water on rockburst were discussed as well. The results showed that when the water saturation of specimens exceeded 0.3, the peak stress and yield stress of the specimens were significantly lower than those of natural specimens. With the increasing of water saturation, the ejecting behavior of small particles decreased, the spalling behavior of small rock slices increased, and the bulging behavior of rock plates weakened during the process of rockburst. Moreover, the volume of rockburst pits decreased, and the particle-size distribution of rockburst fragments became discontinuous. With the increasing of water saturation, the duration of ‘quiet period’ decreased, in which AE impact number dropped significantly before rockburst. Besides, the AE impact number increased at the moment of rockburst, while the accumulated absolute energy and the energy release rate declined, which indicated that the plastic failure of specimen enhanced. The rockburst kinetic energy of specimens decreased obviously with the increasing of water saturation, which exhibited a monotonous linear relationship between the kinetic energy and water saturation. Water mainly showed softening and water wedge effects on rock, and the viscosity of water also affected the ejection of rock fragments.

Key words: rockburst, true triaxial test, water saturation