Experimental study on the failure behavior of rockburst induced by a dynamic disturbance in the circular chamber for deep underground engineering

Abstract

Rockbursts induced by disturbance loads have become a significant engineering issue. Block specimens featuring a circular chamber structure were designed to investigate the effects of the disturbance frequency on rockbursts. The experiment simulated a series of rockburst failure processes through a disturbance load with four different frequencies by maintaining a constant preset confining pressure. The experimental results showed that an increased disturbance frequency intensifies the shear failure response and enhances the rockburst intensity. Furthermore, the particle image velocity technique was used to calculate the ejection velocity. The results suggested that the initial ejection velocity of fragments during rockburst surged by 253 % as the disturbance frequency was increased from 0.005 Hz to 0.625 Hz. The assessment level of rockburst failure transitions ranged from slight to moderate. These results indicated that an increase in disturbance frequency exacerbated rockburst failures. Two mechanisms were proposed to explain this effect. (i) The increase in disturbance frequency elevates the internal friction angle of rock units, enhancing their ultimate energy storage capacity. (ii) Increased energy input causes the energy storage in rock units to surpass the minimum energy required for rock failure, endowing the fragmented rock mass with greater velocity and leading to more intense rockburst failures. Ultimately, recommendations for early warning of rockburst failure are also provided by discussing the microscopic failure mechanisms of rockburst experiments and the rockburst in situ.