FLAC3D numerical simulations of ore pillars at Laronde Mine

On November 27, 2002 Agnico Eagle's Laronde Mine experienced a magnitude 2.6 seismic event. As part of the investigation into the cause of the burst, a high-resolution FLAC(3D) model was created to determine the effect of the mining sequence on stresses in the area of the burst. At this mine, secondary stopes are intended to fail following primary stope extraction. The numerical simulations showed that where remnants were left with non-ideal geometry (through unfortunate but necessary mining decisions), these remnants could be too strong to yield as intended. The FLAC(3D) model showed that one such 3-wide pillar centered at the location of the burst was subject to a local high stress concentration. This provided a unique opportunity to confirm calibration of the FLAC(3D) model. Further modeling also highlighted other areas of the mine where pillars were in a high stress state and recommendations were made to alter the mining sequence to prevent future events.