Assessing stope performance using georeferenced octrees and multivariate analysis

This paper presents the first steps towards a new stope design approach, where stope overbreak (OB; rock mined outside of the design) and underbreak (UB; planned rock left behind) is assessed using statistical multivariate analysis (principal component analysis [PCA] and partial least square [PLS]) and georeferenced data measured at an approximately cubic metre resolution (octrees). Results showed that OB is observed in areas of the stope where there is a large blasting energy proxy, large undercut and towards the middle of the face. UB tends to be observed near the border of the faces and where there is large blasting standoff and toeing of the rings. The resolution of the data and the use of multivariate analysis have enabled the depiction of an accurate interpretation of the variation of stope performance along the design surface, going beyond the simple per face analysis.