ABSTRACT
The high-speed railway line crossing downtown Barcelona was immediate to the main façade of Gaudi's modernist temple of Sagrada Familia. The paper describes the precautions adopted to avoid any damage to the church. The façade was protected by a large diameter pile wall. The performance of this wall against volume losses induced by the Earth Pressure Balance Shield construction procedure is analysed by two computational methods which rely on some fundamental solutions for the elastic half-space. The first 2D plane strain method allows a dimensionless formulation which facilitates a sensitivity analysis and helps to adopt main design decisions. The more general 3D approach described may reproduce the spatial distribution of volume loss, it solves the interaction between general pile foundations and tunnel-induced deformations and it is useful to follow the effect of advancing tunnel excavation on pile foundations (pile walls in particular). The very small settlements observed at the street level (less than 2 mm) are compatible with an overall volume loss of 0.1%. The paper describes also the organization and precautions taken to ensure a very small volume loss. Of particular interest is the procedure followed to maintain in perfect conditions the machine cutting head. It required the construction of deep shafts and auxiliary enclosures to permit the maintenance works under atmospheric conditions
