Geotechnical challenges and monitoring in urban tunnelling: The Florence high‐speed railway project

Tunnel excavation projects in urban environments pose significant challenges due to their potential impact on existing structures, infrastructure, and historical buildings. In Florence, Italy, a high-speed railway underpass is being constructed as part of the Scandinavian Mediterranean Corridor, using earth pressure balance tunnel boring machines. This study highlights the importance of continuous monitoring and adaptive strategies to manage unforeseen soil conditions during urban tunnel excavation, through a focus on induced settlements along Viale Lavagnini and the predictive analysis on the Renaissance-style Fortezza da Basso. Settlement monitoring in the urban area assessed interactions between tunnelling activities and surrounding infrastructure and showed localized variations due to hydraulic perturbations and soil consolidation, while settlements generally remained within design limits. A 3D numerical model was developed for the Cavaniglia bastion at Fortezza da Basso to evaluate the impact of tunnel-induced strains. Results showed the strains were within acceptable thresholds.