The project in Porta Nuova Isola involved the redevelopment of an area that has been historically dedicated to light industrial and craft activities. 70% of the area had recently been assigned as a public park.
Works involved the construction of three underground levels which are to be used as technical spaces and garages and five main buildings for public use, residential and commercial use. Arup was responsible for structural engineering and acoustics.
In the site area, there are two tunnels that belong to the MM2 underground line between the stops “Garibaldi” and “Gioia”, and another tunnel was built for the underground line MM5 on the east side of the site.
The five buildings
The five main buildings include one for public use; one for residential use comprising five or six floors above ground and a number of commercial areas on the ground floor; an office building comprising 10/12 floors above ground and two towers for residential use with 19 and 27 floors, respectively.
The existence of subway line tunnels, a ventilation shaft for the subway and existing buildings surrounding the site created difficulties when designing the foundations and the structure above.
In compliance with the agreement made between the former owner of the site and Metropolitana Milanese, the maximum project excavation depth was defined to reduce the distance between the extrados of tunnels and the excavation base to no less than 3.50m. The presence of the ventilation shaft in via Confalonieri meant taking precautions to avoid damaging the existing structure and that anchoring rods could not be used on the diaphragms that are level with the ventilation shaft.
Ground-borne vibration and/or ground-borne noise from the subway could have affected users of the building, as well as sensitive equipment. People can typically perceive vibration in different forms, depending on the frequency range (relevant frequency range 1 Hz to 80 Hz) and/or as sound: ground-borne noise emitted by vibrating parts of a building. In order to ensure a high comfort level, the buildings’ superstructures have been isolated by dampers at the ground floor level.