Pit slope failure is generally caused by a combination of rock mass and geological structural failure. Conventional pit slope stability design does not represent these failure mechanisms simultaneously, which can result in unrealistic and unsafe optimised pit slope angles.
Dempers & Seymour have developed a design methodology, termed Rock Bridge Ratio (RBR) design which is more precise and representative of pit slope failure. The RBR methodology ensures realistic safe optimisation of pit slope angles for a safe mining environment.
The RBR method estimates the ratio of rock bridge (intact rock) to geological structure within a particular pit slope for design purposes and assigns shear strength parameters for each failure criteria i.e. Hoek Brown and Mohr Coulomb. This enables slope stability analyses that represents both rock bridge and discontinuity shear strength parameters according to the calculated proportion of rock bridge.