Self-initiated static-dynamic state transition behavior and triggering mechanism of strain rockburst using three-dimensional discrete element method

The accurate understanding of rockburst mechanism poses a global challenge in the field of rock mechanics. Particularly for strain rockburst, achieving self-initiated static-dynamic state transition is a crucial step in the formation of catastrophic events. However, the state transition behavior and its impact on rockburst have not received sufficient attention, and are still poorly understood. Therefore, this study specifically focuses on the state transition behavior, aiming to investigate its abrupt transition process and formation mechanism, and triggering effects on rockburst. To facilitate the study, a novel burst rock-surrounding rock combined laboratory test model is proposed and its effectiveness is validated through experiment verification. Subsequently, corresponding numerical models are established using the three-dimensional (3D) discrete element method (DEM), enabling successful simulation of static brittle failure and rockbursts of varying intensities under quasi-static displacement loading conditions. Moreover, through secondary development, comprehensive recording of the mechanical and energy information pertaining to the combined specimen system and its subsystems is achieved. As a result of numerical investigation studies, the elastic rebound dynamic behavior of the surrounding rock was discovered and identified as the key factor triggering rockburst and controlling its intensity. The impact loading on the burst rock, induced by elastic rebound, directly initiates the dynamic processes of rockburst, serving as the direct cause. Additionally, the transient work and energy convergence towards the burst rock resulting from elastic rebound are recognized as the inherent cause of rockburst. Moreover, it has been observed that a larger extent of surrounding rock leads to a stronger elastic rebound, thereby directly contributing to a more intense rockburst. The findings can provide novel theoretical insights for the exploring of rockburst mechanism and the development of monitoring and prevention techniques.