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This paper demonstrates how the use of fracture system modelling can be linked to limit equilibrium analysis of rock slopes susceptible to wedge failure. The use of fracture systems highlights some of the limitations inherent in traditional structural data analysis and representation. Consequently it allows for more comprehensive input data that can be used for stability analysis of rock slopes. In particular the developed methodology addresses important issues such as spatial variability and wedge size distributions. The paper introduces a series of guidelines for interpretation of the results of rock slopes. The proposed techniques arguably result in an improved level of confidence in the design of rock slopes susceptible to wedge failure. KEYWORDS Rock slopes; Wedge failure; Fracture system modelling; Limit equilibrium analysis; Discrete fracture networks CITATION Grenon M, & Hadjigeorgiou J. A design methodology for rock slopes susceptible to wedge failure using fracture system modelling. Engineering Geology (2008) 96(1-2), 78-93.

This paper presents an implementation of a comprehensive engineering approach to the analysis of the stability of vertical excavations in rock. This approach relies in the generation of discrete fracture systems to better capture the structural complexity of the rock mass. The resulting fracture system is consequently linked into a distinct element stress analysis. The particle flow code was selected as it potentially allows greater flexibility in representing a fracture system. In the first example a 3D fracture system was linked into a 2D PFC model. Although this has allowed for an improved quantification of stress structure interaction it necessitated important simplifications which may not be necessarily appropriate. These have been overcome by providing a complete integration of a 3D fracture system to a 3D PFC model. This will potentially lead into a design tool that adequately account for the stress structure interaction on the stability of vertical or near vertical excavations in hard rock. KEYWORDS Fracture system Mining, Vertical excavations, Particle flow code CITATION Hadjigeorgiou J, Esmaieli K, & Grenon M. Stability analysis of vertical excavations in hard rock by integrating a fracture system into a PFC model. Tunnelling and Underground Space Technology (2009) 24(3), 296-308.

The results of structural mapping are used to generate 3-D joint networks. By introducing a virtual excavation in the generated rock mass it is possible to identify all wedges that can potentially be defined at the exposed surfaces of the excavation. The number and size of these wedges are controlled by the geometry and orientation of the excavation, as well as the properties of the generated joint sets and individual random joints. Consequently it is possible to determine the stability of every individual wedge along the span of an excavation. The influence of various reinforcement strategies (type of bolts, reinforcement patterns, mesh, etc.) on the stability of an excavation is quantified. This is a prelude to an economic analysis whereby the costs associated with different stabilization techniques are assessed. This methodology is illustrated by means of three case studies in a polymetallic underground mine in the Canadian Shield.

A major mining slope failure occurred in July 2012 on the East wall of the LAB Chrysotile mine in Canada. The major consequence of this failure was the loss of the local highway (Road 112), the main commercial link between the region and the Northeast USA. LiDAR scanning and subsequent analyses were performed and enabled quantifying the geometry and kinematics of the failure area. Using this information, this paper presents the back analysis of the July 2012 failure. The analyses are performed using deterministic and probabilistic limit equilibrium analysis and finite-element shear strength reduction analysis modelling. The impact of pit water infilling on the slope stability is investigated. The impact of the mining activity in 2011 in the lower part of the slope is also investigated through a parametric analysis.