Advanced Analysis of Damaging Seismic Events in Mines - A Case Study

摘要

Damaging seismic events in mines can have a significant impact on safety and production, therefore it is important to understand these events to help prevent or mitigate the effect in future. Seismicity is caused by changing stress conditions in the local volume of rock. Studying the temporal evolution of seismicity allows us to study the evolving stress state in the volume of interest. In this case study, we investigate these trends before and after a damaging event in a pillar at Carola Mine, Chile. The temporal changes in the stress state are examined through the use of time histories of seismic parameters such and Energy Index (EI) and through the evolution of the moment tensors of the events. The time history of EI, a proxy for seismic stress, shows the stress in a volume around the pillar shortly before the large event is high. EI then decreases rapidly, specifically in the pillar, before stabilizing after the large event. Moment tensor analysis of the events in two pillars show how the P-axes, a proxy for sigma 1, point through different sections of the pillars as the seismicity in the pillars progress. This suggests partial pillar failure which is also supported by the analysis of EI in time and space. By studying the seismicity in these pillars, rich information about the changing stress conditions was obtained. This gives useful information about the support capability of the pillars which can be used for future planning and support design.