Effects of the expected settlements following excavation of a proposed underground subway tunnel in the historic centre of Florence

Florence is a city of average size (about 400,000 inhabitants), with narrow old streets that are quite unsuitable for modern surface vehicular traffic and with a building and monumental patrimony that is among the greatest in Europe. The city is at the centre of a metropolitan area populated by about 1,6 million inhabitants, and is one of the most visited tourist destinations in the world. In order to contribute to solving traffic and mobility problems in its urban area, a group of researchers of the University of Florence carried out a feasibility study on a newly developed underground rapid-transport system, called “Micro-Metro (M)”. The aim of the geotechnical part of the feasibility study was to estimate the absolute and differential ground settlements following excavation of the tunnel, and to evaluate their effects on the building environment. Differ-ent excavation methods were investigated, and typologies and vulnerability of the buildings situated along the layout of the tunnel were examined. The main results obtained from the said study are described in this paper.