Analysis of the vibrations induced by a TBM to refine soil profile during tunnelling: the Catania case history

The present paper deals with the new underground lines under construction in Catania (Italy). The analysed network is under construction with EPBs-TBM machine. the TBM used is a Dual Mode Machine. In order to update the tunneling method with the soil profile, a detailed geotechnical characterization is very important, in particular when a strong lithological alteration during excavation is present (such as in the analysed case history), because tunneling method can be OF (Open-Face) mode for rock formation or EPB (Earth Pressure Balance) mode for cohesive and/or incoherent soil. This paper shows a new methodology to validate the hypothesized soil profile based on a comparison between data obtained by the geotechnical survey and data achieved by HVSR tests on the vibrations induced by TBM on the surface during tunneling. A further comparison is made between data by HVSR tests and by an electric tomography.