Metro C, the General Contractor for the construction of Line C, has been planning and conducting a series of non-destructive tests since 2008 to verify the state and preservation of the monument and to analyze its interaction with the construction of Line C.
The significant campaign of investigations carried out has allowed for the precise definition of the monument’s internal geometry, the determination of materials and types of masonry, as well as their mechanical parameters.
The use of laser scanner technology has provided valuable assistance to the design activity, allowing for an extremely detailed survey of the internal geometry of the sewer system, as well as the elements constituting the masonry of the structure.
Interaction analyses are of great importance in the design of an urban subway line, especially in the historic center of Rome, and serve as the starting point for the design of any support works or settlement mitigation systems, as well as an adequate monitoring system.
The investigation campaign will be completed during the summer of 2018, approximately one year before the excavation of the subway tunnels, temporarily decommissioning a section of the sewer system measuring about 150 meters to extend the assessment of the preservation state to the ancient structures located below the travel surface and potentially carrying out specific consolidations.
The decommissioning will be carried out by installing two vertical metal gates with lateral clamping through self-adhering seals and three metal pipes with a diameter of 500 mm for flow continuity. The proposed solution also includes an alarm system for the sudden rise of the hydraulic head. Control of the flow from the entry of the Via Cavour conduit involves the creation of a single small-sized barrier module equipped with a portion for minor overflows but designed to rapidly breach in the event of large-scale atmospheric events, in accordance with the safety system of the gates for operator safety.
The system, sized as such, is capable of handling a nominal flow rate of 5,000 m³/h against a normalized flow of 1600 m³/h, with a freeboard height of 35 cm.
Finally, during the excavation of the tunnels, an extensive and complex monitoring project for the monument will be implemented within the ancient sewer system, aiming to closely and continuously correlate the monitoring data acquired with the results of the studies conducted during the design phase.
