This paper addresses issues associated with the analysis of rock slopes susceptible to wedge failure. It relies on two case studies to review the state-of- the-art in the use of kinematic, deterministic and probabilistic limit equilibrium methods. Furthermore, it presents a more comprehensive analysis based on fracture system modelling. The presented approach addresses some of the limitations of traditional techniques by providing information on the probability of occurrence of wedges in rock slopes and more realistic estimates of the size of these wedges.


The stability of rock slopes is controlled to a large degree by the structural regime of the rock mass and the slope configuration. Recent years have seen several attempts to develop user friendly tools that can facilitate the analysis and better quantify the probability of failure of rock slopes.

It is recognised that the way a rock mass is characterised has an important influence on the way the input parameters are derived for slope stability analysis tools. The case is made in this paper that our ability to capture and represent the rock mass should be linked to the choice of appropriate analysis and design tools. Two case studies are used to illustrate the impact of different data representation and analysis techniques on the stability evaluation of rock slopes susceptible to wedge failure. The first case study is a highway road exposure in Quebec City in Canada and the second is a road cut near the village of Platres in Cyprus.

The structural regime was defined for each site based on the results field mapping (dip/dip direction, fracture frequency and mean trace length). The identified fracture sets were then used in a kinematic analysis to establish the potential for wedge failure. This preliminary investigation was followed by deterministic and probabilistic limit equilibrium analyses.

This paper advocates the use of fracture systems to better capture and represent the structural characteristics of the investigated rock exposures. Using two case studies the resulting fracture systems were successfully integrated to a developed wedge stability analysis software package. This has facilitated the identification and analysis of more realistic wedges created in the exposed rock mass. Consequently, it is possible to investigate the stability of the two sites using deterministic, probabilistic, as well as fracture system stability analyses.

This content is only available via PDF.
You can access this article if you purchase or spend a download.