PRELIMINARY HISTORICAL AND GEOTECHNICAL ANALYSIS OF THE FOUNDATION OF THE BELL TOWER OF THE MOSQUE-CATHEDRAL OF CÓRDOBA

Poorly documented foundations are a major source of uncertainty in the structural and seismic assessment of historic masonry towers. This study examines the foundation and long-term geotechnical behaviour of the Bell Tower of the Mosque-Cathedral of Córdoba. Historical, archaeological, geotechnical and geophysical data were combined to reconstruct the foundation geometry, the soil profile and the load increases associated with the Islamic and Christian construction phases. Mechanical parameters and groundwater conditions were defined using site-specific boreholes, laboratory tests, MASW 2D profiles and available data. A three-dimensional model was developed in PLAXIS 3D. The Mohr-Coulomb and Soft Soil models were compared. The foundation system is mainly composed of sandstone masonry with lime-based levelling layers. The foundation reaches a depth of approximately 7.70-8.10 m and rests on dense gravel (N_SPT = 50). The preliminary analyses provided settlement values and an estimate of the tower tilt. These results were compared with evidence from in situ inspections and photographs. The comparison between the two constitutive models was used to assess their influence on the predicted foundation response. The study provides a geotechnical basis for assessing the long-term behaviour of the foundation. The results will support the derivation of equivalent foundation stiffness for future structural and seismic soil-foundation-structure interaction models, as well as preventive conservation and risk-based monitoring.