Keynote Lecture – Examples of preserving historic buildings from the impact of tunnelling
The construction of the high-speed railway line from Barcelona to the French border, involved the excavation of tunnels crossing the central districts of the cities of Barcelona and Girona. Some historic buildings were potentially affected by the excavations and a great effort was made to reduce that impact as much as possible. The lecture presents 3 cases of very different buildings and the corresponding Geotechnical Engineering solutions adopted: an old farm house from 13th century, where an underpinning system was designed; the Sagrada Familia Basilica, where a barrier of stiff piles was built to protect the world heritage monument from the tunnel, and the building La Farinera, from early 20th century, where a compensation grouting was carried out. Preserving those monuments was one of the main challenges of the whole project. The impact of the tunnel on them was negligible thanks to an elaborated design and to the tight control during construction. On the one hand, the design involved the use of 2D and 3D finite element analyses, using advanced constitutive models considering the soil stiffness at low strains and performing an intense site investigation. On the other hand, the control of the tunnel boring machine was intense as well, with an independent external team replicating and checking the operations of the driving team inside the TBM. Overall, it is a good example of how to carry out large and complex construction projects while respecting the heritage of historic buildings.