Laboratory and numerical modelling of the lateral spreading process involving the Orvieto hill (Italy)

The results of a study carried out in the cliff rock of the medieval town of Orvieto (Umbria region, Italy) are here presented. The Orvieto hill is involved in a lateral spreading process as a consequence of its geological setting, due to the overlaying of a rigid 60 m thick tuff slab on plastic overconsolidated blue clays. In order to reconstruct the stress path experienced by the Orvieto blue clays during their geological evolution, a not standard laboratory test was performed, by a triaxial device. The obtained function was used to perform a sequential FDM numerical modeling, whose findings are consistent with the actual site conditions. These findings point out the significant contribution of both laboratory tests and numerical modeling in order to reproduce the present stress-strain conditions of the hill involved in the lateral spreading process, and then to better define the engineering-geology model of the Orvieto hill.