Study on the spatial relationship between potential and actual rockbursts in a deeply buried hard rock tunnel
摘要
Rockbursts pose serious threats to the safety of personnel and equipment in deep underground engineering, and accurate identification of potential rockburst locations is crucial for precise early warning and effective mitigation. This study investigates the spatial correspondence between potential and actual rockburst occurrences by analyzing two representative cases of strain-type and structural plane-type rockbursts. Through detailed analysis of the relationships among microseismic events, actual rockburst locations, and geological survey results, the mechanisms by which potential rockburst points evolve into actual events under different geological conditions are revealed. Methods for identifying potential rockburst locations and strategies to eliminate or reduce rockburst risks are proposed. Key findings include: (1) Strain-type rockbursts can be predicted through “point-to-point” early warning based on the locations of high-energy microseismic events, whereas structural plane-type rockbursts require a “regional” warning due to the distribution of high-energy events along structural planes or their slip paths; (2) Low-energy microseismic events help visualize stress transfer paths or concentration zones and fill the temporal gaps between successive rockburst occurrences; (3) Structural defects such as heterogeneous rock mass transitions, cryptic fractures, and structural planes can readily trigger rockbursts when located close to or intersecting free surfaces. Proper control of the distance between stress concentration zones and free surfaces, in combination with optimized blasting distance, can effectively reduce or even eliminate rockburst risks. These results provide valuable insights into rockburst mechanisms, improve early warning accuracy, and contribute to the mitigation of rockburst hazards in deep underground engineering.