Preliminary assessment of primary stope performance for a seismically active mine: 53rd U.S. Rock Mechanics/Geomechanics Symposium

Evaluating stope performance is important for improving stope stability, production efficiency, and profitability. Underground mines are Operating at greater depths where workers and excavations are exposed to hazards such as seismic events, which are not addressed by standard empirical stope analysis. A stope database was created for 114 primary stopes (2.7–3 km below ground level) mined between November 2013 and August 2018. It considers geometrical, geomechanical, operational, and seismological parameters. To assess stope performance, reconciliation between the mined and the designed stope geometries was performed for the entire stope volume and on a surface-by-surface basis. Common stope performance metrics such as overbreak (OB), underbreak (UB), and equivalent linear overbreak sloughing were measured, as were other metrics like rock and backfill overbreak. Results of the univariate analysis showed the OB for the hangingwall of stope type A and the UB for the east and west walls of stope type B were the critical underperforming parameters. Bivariate analysis showed trends linking OB to Richter scale seismic events, rock quality designation, stand-up time, and spatial distribution. Trends were also found linking UB to planned volume and borehole standoff. Copyright 2019 ARMA, American Rock Mechanics Association.