Analysis of subsoil vibration-transmission characteristics by monitoring tunnel excavations in an urban area context

The complexity of the models used, the large number of parameters considered and the detail of the analyses that are performed when making predictions of the vibrations induced by an underground metropolitan railway line in service are not always a guarantee for the adequacy of design choices and certainty of the induced levels of disturbance. Similarly to the methodology already considered as valid for the prediction of induced subsidence during tunnel boring, a research programme has been set up to address the issue of correlating subsoil characteristic parameters, among those usually investigating in tunnelling activities, and transmission of vibrations. Such an approach should allow the difficulties connected with the non-homogeneity and variability of materials making up the subsoil to be overcome, both in terms of composition and anisotropy. The availability of a database populated with information on subsoil characteristics and corresponding vibrations should allow the identification of correlations by means of statistical processing, regardless of detailed knowledge on the underlying phenomena. The preliminary considerations reported here confirm that the approach could be further explored.