This Master’s Degree thesis provides the return experience of the rock mass and supports evolution, within a tunnel of small diameter and high overburden. It is an exploratory excavation, realized between 2013 and 2017 for a length of 7km in severe micro climatic conditions. The tunnel, named La Maddalena 1, was realized for the characterization of the Ambin Massif, which is to be crossed by the base tunnel of the TELT project, developed between Italy and France. The tunnel was excavated adopting a mechanized approach with a rock TBM, after which the structure has been maintained partially inactive until the present day.