Untersuchung einer potenziellen Korrelation zwischen bergbau-induzierter Seismizität und Produktion im Bergwerk Kiruna für das gesamte Bergwerk und für einzelne Abbaublöcke

Abstract

AbstractThe creation of cavities in the underground results in stress redistributions and energy changes in the rock mass. Zones with increased stresses and zones with lower stresses develop. The energy changes manifest themselves amongst others in changes in potential energy, absorption of energy in the formation of fracture zones, and release of energy such as seismic energy. To prevent damage to infrastructure and personnel, it is important to understand the mechanisms of energy changes as a result of mining. As far as seismic energy release is concerned, it is important to understand to relationship between large scale mineral extraction and mining induced seismicity. One coarse way to do this is to correlate for specific areas the cumulated tons of mined rock multiplied by the depth of extraction and multiplied by the gravitational acceleration to get the unit of energy, which is a rough assessment of the mining-induced energy changes, with the cumulated released seismic energy, which is derived from the seismic monitoring system. This correlation is studied for Kiruna Mine on a mine-wide scale and on an extraction block scale for the years 2014 to 2020. The results show that there is a reasonable correlation between the mining-induced energy changes and the seismic energy release not only on a mine-wide scale but also on an extraction block scale. Periods of decreased seismic energy release are followed either by a period of increased seismic activity or by one or a series of large seismic event. Accordingly, periods of decreased seismic activity can be considered as an indicator for a likely increase in future seismic activities. More detailed investigations should be made to find out the cause for the lack of energy release. A disadvantage of this method is that it does not reveal the exact area and reason for the decrease in seismicity. Therefore, additional rock mechanics analysis is needed to understand the background of the change in energy release.