Study on Rockburst Nucleation Process of Deep-Buried Tunnels Based on Microseismic Monitoring

摘要

The objective of this study was to investigate the rockburst nucleation process and provide a theoretical basis for its prediction. A microseismic monitoring system was established in deep tunnels at Jinping II Hydropower Station. Using a digital multichannel microseismic monitoring system and monitoring technique, twenty-four-hour continuous real-time monitoring of microseismicity was realized in diversion tunnel #3. Substantial microseismic monitoring data were acquired to study the macroscopic instability failure mechanisms in the rockburst nucleation process in terms of dynamic crack propagation, including microcrack initiation, development, propagation, shear zone formation, and coalescence. The intrinsic relationship between the spatiotemporal evolution patterns of the microseismicity and the rockbursts was preliminarily explored. The monitoring and analysis results indicated that the driving source of certain rockbursts could be expressed as the combined results of the local rockburst energy and the transfer energy; that is, E-drive = E-local + E-transfer. Strong rockbursts can induce the recurrence of rockbursts in nearby locations. In addition, a comparative analysis of the formation and failure mode of molds in underground caverns was performed using the finite element analysis program RFPA. Based on this engineering study, we verified the feasibility of applying microseismic monitoring to rockbursts in deep rock tunnels.