Pillar design for a nuclear waste repository in hard rocks

Pillar design is traditionally carried out by empirical methods using a "back-analysis" technique. This approach, while practical in an operating mine, may not be suitable for a nuclear waste repository where pillars must withstand: excavation induced stresses; thermal stresses generated by the heat from the nuclear waste; dynamic stresses associated with seismic events; and glacially-induced stresses. The designers of these pillars need a thorough understanding of the rock mass failure process in order to develop a comprehensive failure criterion for pillars. A review of pillar design suggests that current practice may not be adequate, at a nuclear waste repository, to ensue pillar performance is in accordance with the safety requirements.