Observed Performance of a Deep Excavation in the Historical Center of Rome

The C Line of the Rome underground underpasses the historical city center, facing significant problems for the presence of archaeological artefacts and the necessity to prevent damage to the historical and monumental heritage. This paper describes the field performance of a 30-m-deep excavation that has been constructed at a short distance from the Aurelian Walls at Porta Asinaria (third century). An extensive instrumentation program was conducted during construction, as well as field observations including deflection of the diaphragm walls, ground movements, pore water pressures, settlements, and rotation of the Aurelian Walls. Observed ground settlements and diaphragm wall displacements were smaller than those monitored in other case histories worldwide, inducing no damage to the Aurelian Walls. The lessons learned from this case study showed that a stiff retaining system and a strict control of the construction sequence were the key to minimize the effects of a deep excavation with millennia of history at risk