A reliability analysis of the dilution graph method for open stope design: A case study

The equivalent linear overbreak slough (ELOS) graph is a commonly used empirical design method for open stope design. Nevertheless, this method can lead to poor design performance when the geotechnical domain data lacks confidence. This is due to the inherent variability of the design input parameters, which should be considered for more reliable stope design. Hence, in this study, the First-Order Reliability Method (FORM) is used to determine the reliability index and the probability of unplanned dilution level associated with the design for each geotechnical domain. The Maleyevsky mine, located in northeast of Kazakhstan, is used as a case study. The parameters used for the analyses are the Modified Stability Number (N'), Hydraulic Radius (HR), and the actual dilution. The results indicated that the reliability indices and the probability of unplanned dilution occurrence vary between 0.1-4.63; and 0.0001% - 46.02%, respectively, depending on the rock domains. The results were in agreement with the field observations. It is concluded that the reliability-based design method could serve as a tool in the design of the open stope in connection with minimizing unplanned dilution.