Safeguarding of the AurelianWalls at Porta Asinaria from conventional tunnelling

Construction of the line C of Rome underground is being carried out in a complex context due to the presence of archaeological artefacts, historical buildings and monuments of invaluable value. Along the contract T3 of the line, between the shaft 3.3 and San Giovanni station, two tunnels have been excavated for a length of about 140m following a three step procedure: excavation of two small diameter tunnels with a mini TBM; soil improvement via low-pressure cement grouting; and conventional excavation of the two line tunnels in the improved soil. The tunnels, excavated at a depth of about 25 m, reach San Giovanni station passing at a short distance from the ancient AurelianWalls. This paper presents the displacement measured at ground surface during the construction activities, showing the efficiency of a protective barrier made by a line of piles in reducing the movements induced by tunnelling in the AurelianWalls.