David Saiang

Probabilistic analysis of open stope stability using numerical modelling

A probabilistic approach is presented for the analysis of open stope stability. The approach considers the inherent variability and uncertainty which are typical of rock mass properties. In this study, a series of numerical analyses were performed using FLAC to study the stability of open stopes while taking into account the variability in the rock mass properties. The rock mass was divided into six strength classes: three classes for the host rock and three classes for the massive sulphide ore. Each class was randomly distributed to the elements in the FLAC model. The host rock-to-massive sulphide ore ratio is envisaged to have a strong influence on the stope. To verify this, three cases of different ore percentages were considered and the results compared. The results, which were presented as Probability Density Functions (PDFs), indicate that the zones of low stiffness show high range of displacements and that the increase in the percentage of the ore significantly affects the stability of the stopes.