Effect of mining geometry on mining induced burst events – A case study

Rockburst is a complex problem which underground mines face around the world as they reach deposits at greater depths. Based on literature, it is well established that rockburst can be caused by numerous factors most notably geological features, mechanical rock properties, induced seismicity, and mining parameters. In this research, the Young Davidson (YD) Mine in Northern Ontario, Canada is used as the case study. The mine experiences seismic events at relatively shallow depths of less than 1 km. In the current study, rock burstability is examined through a comprehensive rock testing program of the different YD Mine lithologies. It is found rock burstability potential is low to moderate at best. A 3D mine-wide numerical model was then built and the updated mechanical rock properties as well as measured in-situ stress regime were used. The stress analysis revealed that high stress concentration occurs in the ore pillars. Seismic events were attributed primarily due the following factors: the stress state as a result of the mining geometry, the nature of the sublevel stoping system leads to highly stressed secondary stopes and the oblique orientation to the orebody strike of the in-situ stress tensor with an exceptionally high horizonal to vertical stress in-situ stress ratio. These findings support the hypothesis that mining geometry can be an independent cause for mining-induced seismicity regardless of rock properties.