Some back analysis techniques applicable in geotechnical engineering are summarised, considering both their deterministic and probabilistic aspects. The discussion is limited to static conditions. First, two alternative back analysis approaches are described, in a deterministic context, referred to as "direct" and "inverse" techniques. Subsequently, a probabilistic Bayesian technique is discussed which aims at investigating the influence of the experimental errors on the results of back calculations. Finally, two appli-cations to actual tunnelling problems are summarised
