Assessment of Surface Deformations Induced by Tunnelling with Analytical and Finite Element Analysis

Underground metro tunnel failures in recent years have caused significant economic losses and posed serious risks to surface structures, highlighting the importance of accurately predicting tunnelling-induced ground deformations. Surface settlements occurring during TBM excavation may adversely affect existing infrastructure, particularly in sensitive urban areas. This study evaluates surface deformations induced by a TBM-driven metro tunnel as a case study, explicitly considering tunnel–structure interaction at locations where piled bridge piers are present. Due to site sensitivity, topographic monitoring was conducted during TBM passage, and measured settlement data were used for assessment. Settlement analyses were performed using the Peck (1969) empirical method and finite element modelling in Plaxis. Two constitutive soil models, Mohr–Coulomb (MC) and Hardening Soil (HS), were adopted to compare their predictive performance. The results show that the MC model predicts the highest surface settlements, whereas the Peck (1969) method provides results close to those obtained with the HS model, despite not explicitly incorporating structural loads. From the finite element tunnel models, it was determined—particularly from the two coordinate routes—that the HS model achieved prediction accuracy of up to approximately 95% compared to the measured values. Overall, the Peck approach and the HS model yielded more consistent predictions than the MC model for the investigated conditions, emphasizing the importance of appropriate soil model selection in finite element analyses of tunnelling-induced settlements.