The importance of variability in soils and rocks has been widely acknowledged and the object of numerous studies. In
this paper, the impact of modelling rock variability is assessed by performing numerical analysis of the excavation of a deep circular
tunnel in a rock mass characterised by a uniform and isotropic stress state. The variability is introduced in the analyses by considering
random fields of variable parameters generated using the Local Average Subdivision (LAS) method. The results of the performed
analyses are compared against the results of a traditional deterministic approach where uniform properties are considered, both in
terms of displacements around the excavation and forces in the tunnel lining, so that the influence of introducing variability can be
assessed. Finally, a parametric study is carried out in order to evaluate the influence of the parameters adopted in the generation of
random fields, such as the standard deviation, the spatial correlation distance and the ratio of anisotropy.