Structural engineering and geology applied to the static problems of the Etruscan “Tomba dell’Orco” (Tarquinia, Central Italy)

The Etruscan Tomba dell’Orco was discovered in 1868. However, soon after discovery, part of its ceiling collapsed. An investigation was thus conducted with a view to assessing its safety conditions and permitting visitors’ access. Petrographic and physico-mechanical features of the local weak sandstones and mechanically more resistant calcareous sandstones “macco” were determined. Field mapping, drill-holes and geophysical prospecting helped reconstruct the stratigraphy of the volume where the tomb was excavated. The stability of the tomb basement is given by a thick macco layer. A few dm macco layer was identified above the ceiling. A model was then prepared with the Plaxis 2D V8.6 software. The safety coefficients calculated along two cross-sections of the tomb indicated that the margins for the tomb stability are reasonable.