The original Mathews method for predicting stope stability has been extended and now contains 483 open stoping and caving case histories over a wide range of geotechnical conditions and stope dimensions. The mathematical framework upon which the Extended Mathews stability graph is based and the large database has facilitated examination of a number of outstanding issues surrounding the application of empirical stability graphs. This paper summarises how the framework of the Extended Mathews stability graph framework has been applied to quantify the effect of stress relaxation upon excavation stability, examine site-specifi c effects and highlight the poor correlation between stability graph parameters for narrow stope stability. Back-analysis of case studies where stope surfaces were relaxed has enabled the effect of stress relaxation upon excavation stability to be quantified and bounded. Detailed statistical analyses have demonstrated that a reliable stable-failure boundary requires at least 150 case histories, of which a minimum of 10% should be unstable stope surfaces. Marginal site-specifi c effects were observed for the operating conditions captured within the database. Apparent site-specifi c effects noted in previous literature were found to be attributable to operating conditions inadequately represented in the database. Statistical analysis of overbreak from 115 narrow-vein case studies has demonstrated that operating conditions in narrow-vein mines differ suffi ciently to warrant changes in the model framework to account for undercutting of stope walls and drill and blast parameters. Backfi ll abutments were found to behave the same as solid rock abutments
