Investigations and stability analysis of San Marcellino cavities in the historical centre of Naples

The historical centre of the city of Naples is characterised by a network of underground anthropogenic cavities. Most of these cavities are stable and safe but sometimes for several reasons they are at least partially responsible of the occurrence of instability phenomena such as sinkholes and collapses. The opening of a sinkhole in the cloister of the Ancient Royal Boarding School (known as Educandato Reale of San Marcellino) led to fears of instability in the known underlying cavities. Therefore, a site investigation program was carried out to ascertain the causes of the event. The investigation concluded that the sinkhole was not related to the underneath cavities, located in tuff between 12 and 20 m beneath the main building. Nevertheless, due to the interest raised by the preliminary safety assessment, such a cavity system was selected within the MOSCAS project for further studies. The results of the site investigations and the stability of the cavities determined via FEM code Plaxis 2D are presented and discussed in this paper.