DESIGN METHODS FOR STOPES AND SILL PILLARS WITH APPLICATION TO THE ZINKGRUVAN MINE, CENTRAL SWEDEN

The design of pillars in cut-and-fill mining and open stoping in verti cal and subvertical orebodies is of vital importance in optimizing min ing operations. The primary requirement for a good and reliable design technique is the ability to represent the actual physical behaviour o f the pillar. In this paper, a new methodology for stope roof and sill pillar design is proposed for the Zinkgruvan Mine in Sweden. Studies of failure modes, local geology and rock mass characteristics were car ried out to correlate failure modes to different geomechanical environ ments. For preliminary design, crude and ready-to-use stress level cri teria were extracted from simple linear elastic modelling. More detail ed modelling was used to simulate observed failures in a mechanically realistic manner and, at the same time, to help identify the fundament al failure mechanisms. Once the correct models and input parameters we re identified, a set of guidelines on choice of model and parameter va lues were produced. The models can be used for design of new mining ar eas at Zinkgruvan, and the methodology could also be applied to other mines with similar geomechanical conditions.