The proposed paper is aimed at analysing a rock slope failure that occurred in a sector of an open pit quarry. The failed rock volume was not large, it had a significant impact on the mining operations and the safety of the district road which runs very close to the quarry site. An evaluation of the possible failure mechanisms is given, which was based on a structural description of the rock mass, a mechanical laboratory characterisation of the rock and of rock joints, and on the environmental and exploitation condition. The analysis referred to schemes that could explain the degree of instability of the rock slope. Kinematical analyses, block theory and limit equilibrium were applied and evaluations were also obtained by using DEM models to estimate the static behavior and possible effects induced by quarry blasts of the rock slope.
Open pit quarry exploitation for industrial mineral production involves large and rapidly developing excavations whose interaction with the rock mass and the overall environmental condition sometimes induces failure in the excavated rock slope. When the kinematics of the failing rock volume is suitably outlined by continuous joints, as in the case of planar sliding, classical limit equilibrium techniques and the block theory can be profitably applied (Hoek & Bray 1981, Goodman & Shi 1985), otherwise numerical techniques should be exploited using widely validated software programs (e.g. Itasca 2000, RocScience 2002). These techniques range from equivalent continuous approaches, to block models for discontinuous systems such as DEM (Cundall 1971) and DDA (Shi & Goodman 1985), from fracture mechanics approaches for intermittent rock joints (Scavia 1995) to hybrid continuous discontinuous models, which have recently been applied for the analysis of a massive rock slope failure (Eberhardt et al. 2004).