NUMERICAL MODELLING OF SILL PILLAR FAILURE OF THE NIOBEC MINE AT ST-HONORE, QUEBEC, CANADAAll the Niobec Mine, St-Honore, Quebec, Canada a sill pillar failed, snapping standard Swellex rockbolts, set at5 ft by5 ft spacing , the C-102 sill pillar failure w

All the Niobec Mine, St-Honore, Quebec, Canada a sill pillar failed, snapping standard Swellex rockbolts, set at5 ft by5 ft spacing , the C-102 sill pillar failure was located between600 ftand700 ftlevels. Information was collected and a back analysis study was conducted. A 2-dimensional, finite element, numerical modelling software system called e-z tools was selected to model the failure because it has the facility to simulate cable/rock-bolts. A parametric study, to determine the causes of failure, was undertaken and focused on the redesign of ground support. Cable bolts of 30 ft length with5 ft. by ft. spacing were found tobe ari appropriate mode of internal ground support, the paper providesdetails of the input data, numerical modelling technique and results of the study in the form of safety factors, using Hoek-brown empirical failure criterion, forjointed rock mass, stresses,displacementsand axial forces in the bolts. Conclusions drawn were based on those results and recommendations were made to improve the existing stability condition