Box Tunnel under XVII-th century arch Trujillo bridge at Lima (Peru)

A heavy lifting operation was performed to build a concrete cut & cover tunnel underneath an ancient XVII- th arch stone bridge, Trujillo Bridge, at Lima, Peru. Two piers, 3000 tons each, were temporary shored by

300 mm diameter piles. Thirty seven 400 tons synchronized hydraulic cylinders worked together compensating the piers settlements, limiting the movement during the whole operation between -5 mm and + 2 mm, with no perceptible damage to the historical bridge. Six prestressed galleries per pier were manually excavated through the pier foundations to bridge the loads to the hydraulic devices supporting beam. Due to the high seismic hazard (0.53g PGA for 1000 years return period), a temporary earthquake resisting system has been installed throughout the whole construction process.