ABSTRACT
The prediction of rock formation behaviour due to changes in the stress/strain field caused by the excavation of an underground structure is complex. The main reason for this complexity is related to uncertainties concerning rock mass characterisation and, in particular, definition of geomechanical parameters which is normally performed using laboratory and in situ tests, complemented by the use of empirical rock mass classification systems (Barton et al., 1974; Bieniawski, 1989; Hoek et al., 2002). These different methods are used in several stages of design to reduce uncertainties related to the rock mass behavior.
