An under-excavation model for The Leaning Tower of Pisa

Abstract

The Leaning Tower of Pisa is a complex case and has due to its nature been analyzed for decades through both manual and numerical testing. Resent FEM analyses have still not succeeded in modeling all of the stabilizing measures that have been performed on the Tower foundation and are important in relation to the numerical recreation of the measured Tower deformation. One of these is the under-excavation procedure and a new approach to this procedure has been created and modeled in simplified FEM analyses. The new method is implemented in the constitutive Anisotropic Creep Model and has been tested and optimized to make it applicable in a full 3D model of the Tower.Testing performed has shown to be especially sensitive to the choice of mesh refinement, and also to the chosen tube size and in order to obtain accurate extraction values a finer mesh must be used or tube measures must be increased. The new under-excavation procedure has so far not been implemented in the full 3D model of the Tower. This model is complex and thus time demanding and is so far using the internal Soft Soil Model in PLAXIS.