ABSTRACT
During the underground work design, the first step in characterizing the behaviour of the materials involved in the excavation (rock masses and/or soils) consists in defining the geological conceptual model, in which an in-depth knowledge of all the geological and hydrogeological aspects, as well as all the problems and hazards deriving from them, is summarized. Only a correct reconstruction of the geological conceptual model can lead to optimal design solutions from all points of view: the identification of the best location, the choice of the type of portal, excavation technique, lining, stabilization works, consolidations, etc. In this chapter, the geological, geomorphological, tectonic and hydrogeological aspects and the hazards deriving from them (for example fault crossing, swelling, squeezing, rock burst and gas) are examined. Moreover, a short description of both geological and hydrogeological investigations and tests aimed at characterizing the material is presented. Finally, the phenomena by seismic events, potentially affecting the underground constructions, are taken into account.
