From geological and historical data to the geotechnical model of the Two Towers in Bologna (Italy)

This paper outlines the multidisciplinary approach developed for the definition of the geotechnical model of the foundations of Asinelli and Garisenda towers in Bologna. Historical information and previous site investigations were collected and analysed. Then a new geotechnical investigation was carried out in 2016, which enabled accurate identification of the soil-foundation systems of both towers. In addition, the geotechnical soil properties were investigated taking into account the geological setting of the area. The latter, enabled the recognition of prominent stratigraphic markers within the ~100 m thick alluvial succession beneath the Two Towers foundations, thus providing a new key to soil mechanical properties. This study enabled the identification of the significant features of foundation structures and subsurface stratigraphy, characters of authenticity of the Two Towers which should be carefully preserved in any future conservation strategy of these valuable monuments.