Likelihood statistic for interpretation of the stability graph for open stope design

摘要

The stability graph method for open stope design is an empirical method, and its interpretation is highly subjective. Subjective interpretation of the stability graph has resulted in unknown risks from human bias and inherent errors. Users of the stability graph method for open stope design are for example, given the wrong impression that if a stope plots in the stable zone, that stope is definitively stable and its performance in service presents no risk of instability. Statistical tools exist that can be applied to interpret the stability graph and significantly minimize the subjectivity in the stability graph method without making it seem more rigorous than it is currently perceived. This paper identifies the Baysian likelihood method as a powerful tool for a statistical interpretation of the stability graph, and uses the extended database based on the Potvin (1) calibrated stability graph factors to illustrate the method and its benefits. Mathews and his co-workers (2) in Golder Associates introduced the stability graph method of open stope design in 1980. The stability graph is a plot of a stability number N against a shape factor HR.