Polyhedral modelling of underground excavations

The use of key-block theory for the analysis of blocky rock mass structures in mining and civil engineering is well established. Such methods have traditionally been used to analyse the stability of rock blocks at free surfaces only. These methods have also been limited to the analysis of relatively few discontinuities, usually assumed to be infinitely persistent.Development of more advanced algorithms has removed these limitations and allowed the development of a modeller capable of handling multiple curved, finite persistent discontinuities. We discuss this modeller and its capability of predicting the existence of polyhedra with unlimited facets and morphologies. This paper describes the use of this polyhedral modeller for the study of the stability of an underground excavation and offers significant advantages over the algorithm recently reported by Menéndez-Díaz et al. (2009) [3] which is restricted to the analysis of pentahedral blocks formed by four discontinuity sets.