Classification of non-oriented fractures along boreholes to joint sets andits success degree

The feasibility and safety of a mining project or the choice among alternat ive mining methods could depend on the joint densities and orientations wit hin the rock mass. The accurate determination of the orientation of all joi nts is technically difficult and often economically unrealistic. This study presents a new approach in classifying joints found in exploration borehol es as joint sets, whose statistical distribution is determined from a few h undred oriented joints in boreholes. Each non-oriented joint is classified as belonging to a set based on its "a posteriori" probability of membership in a Bayesian framework. The theoretical rate of success of the classifica tion can be computed for each possible borehole orientation and plotted on a stereonet to determine the optimal orientation of new boreholes. The perf ormance and limitations of this approach are investigated. An application e xample at the Mont Porphyre's large scale block-caving project at Gaspe Min es, Quebec, Canada, is studied.