Analisi geologica e geomeccanica preliminare per il progetto della ferrovia delle Dolomiti tra Auronzo e Somadida (BL)

A project for a new railway from Calalzo to Cortina has been proposed in order to promote the tourism in the Dolomiti area. The plan was realized by the Department of Civil Engineering of the University of Padova. The project is a single track railway line and includes outdoor sections, tunnel and bridge sections. In this thesis is analysed the railway part between Auronzo and the Somadida Forest has been analysed conducting preliminary geological and geomechanical studies. Aim of these studies has been the identification of the existing or potential geological, geomorphological and engineering geological problems as the basis for the future executive planning. At the beginning geology and geomorphology of the area have been studied on the base of the existing geological maps integrating them with direct field analysis where and when necessary. The outcropping rocks have been classified according to the existing international regulations, considering the results of both field analyses and some laboratory tests. Then, the problems along the railway layout have been identified. The main problems result to be mainly constituted by the geomorphological activity of the area (debris flow and rock falls) and by the stability of the tunnel crown and invert. Debris flows are widespread in the area, as it shows the ideal conditions, both climatic and lithological, for the trigger of these phenomena. This type of phenomena are particularly dangerous due to their velocity and relatively large volumes. A preliminary analysis of the triggering conditions has been carried out considering intense storm as the only one trigger. Common are also snow avalanches, mapped by the Basin Authority, but not considered in this phase of studies. However, it has been observed that they generally follow the debris flow creeks. As a first approximation, the risk for rock falling has been statistically analysed with the software Rockfall whereas the tunnel stability conditions has been 8 performed using a finite differences software (FLAC). A preliminary simulation of the tunnel stability in rocks has been performed also using a distinct elements software (UDEC) in order to better considering the effect of the discontinuities geometry and mechanical properties. Concluding, the geological and engineering geological setting of the examined area are such that a new railway may be planned. However, while the problems connected with the tunnel digging out and with rockfalls seem to be not too much complex, and then resolvable, the future trigger and development of debris flows must be carefully analysed and efficient countermeasures forecast.