ABSTRACT: Common back analysis techniques, such as empirical stability graph methods, are limited in their ability to identify and quantify the relative contributions of the various factors that influence excavation performance. A comprehensive back analysis of existing stoping operations was deemed necessary to critically assess key contributing factors to existing and future performance of open stoping at Kanowna Belle, such as drill and blast, development undercutting, induced stress rock mass damage, rock mass quality, and large scale geological features. The back analysis strategy firstly adopted targeting earlier, shallower, primary- secondary stoping blocks to potentially minimise the contribution of the effects of stress induced rock mass damage on stoping performance. In this regard, Block A stopes were chosen for this critical review. Performance of Block A stopes was assessed through analysis of post extraction geometric data, utilising the results of CMS surveys. The studies undertaken highlight the impact of various stress-path dependent damage mechanisms, in situ rock mass quality and the influence of stope-scale geological structure on open stope performance.
1 INTRODUCTION
Common back analysis techniques, such as empirical stability graph methods, are limited in their ability to identify and quantify the relative contributions of the factors that influence excavation performance, such as: stope geometry, development location and undercutting, rock mass characteristics, in situ and induced stresses, large scale geological structures, rock reinforcement, drill and blast processes, and time dependency (Clark & Pakalnis 1997). The purpose of this paper is to report on an initial back analysis study of Kanowna Belle Gold Mine Block A long-hole open stopes, utilising 3-D linear elastic numerical modelling, together with models of rock mass quality and large-scale geological structures. 1.1 Kanowna Belle underground operations Underground operations at Kanowna Belle Gold Mine (KBGM) are situated beneath the Kanowna Belle Open Pit, with large-scale long hole operations commencing in 1998.
