ABSTRACT
In this chapter, it is first emphasised the importance of basing the tunnelling design on sound Risk Analysis and Management procedures, also describing how they are significantly improved using an early-activated, systematic approach, starting from the very beginning design phase. A relevant source of risks comes from uncertainties in the reference scenario related to the geological and geotechnical conditions before construction. It is then given a synthetic list of some, main, possible geological, hydrogeological and geotechnical hazards, to be considered in the preliminary design phases, also discussing a case history of preliminary Risk Analysis along a major base tunnel, with a specific focus on squeezing and brittle, fragile rapid failure.
