Microseismic and precursor analysis of high-stress hazards in tunnels: A case comparison of rockburst and fall of ground

In rock engineering, microseismic monitoring technology has been extensively applied for the interpretation and forecast of rockburst hazards. However, highly stressed hard rocks could suffer dynamic geological hazards (rockburst) and gravity-driven geological hazards (fall of ground), both of which have distinct developmental processes and precursory features that await comprehensive exploration. Hence, in this study, we adopted microseismic monitoring and an advanced method based on the source parameters of seismic energy, seismic moment, and apparent stress (the EMS method). The source parameter space was constructed to ascertain microseismic events as stress-adjusting, deformation-driven, or energy-releasing type. The evolution of the event type and the microseismic path precisely revealed the characteristics of the hazard development. In a case study of a deeply buried tunnel, we analyzed the process by which high-stress hazards occur using the proposed method and distinguished between the respective microseismic characteristics of the rockburst and fall of ground in the development and occurrence stages. Finally, we proposed the key precursory of rockburst and fall of ground in high-stress rock masses. While deformation-driven events increase notably in rockburst, stress-adjusting events are dominant in fall of ground. Overall, this study could facilitate precise interpretation and warning about different high-stress hazards and provide effective measures to curb the development of hazards.