VENEZIA STATION: THE INVESTIGATION CAMPAIGN CURRENTLY UNDERWAY
In the surrounding area of the “Piazza Venezia” station, the first phase of the investigations have shown a complex situation, both in the central area of “Piazza Venezia”, and above all, in the area of “Piazza Madonna di Loreto”. The investigations have been carried out in several phases, allowing the exploration of an important multi-layered urban sector, from the Repubblican age to now. In particular, the excavations have brought to light a public building in the form of a rectangular hall with two staircases inside. Used for cultural activities it is a space known as the Athaneum of Hadrian.
The archaeological investigations, carried out from 2008 to 2013, were concluded with the request of the Superintendence to evaluate and encorporate the ancient structures found as part of the future Venezia station. Following the renewed interest shown by the Capitoline Administration and the Financing Bodies in the realisation of the Fori Imperiali-Venezia functional section, starting in December 2019, a campaign of archaeological and geognosticological surveys and investigations with regard to the design of the new “Piazza Venezia” station was launched. The request for additional archaeological investigations by the Superintendence stems from the desire to create an “archaeological station” that connects underground via a museum route the “Palazzo Venezia”, the “Vittoriano”, the “Foro di Traian”o and that includes, inside the station body, the structures found during the excavations.
The additional investigations planned concern:
- investigations on the structural and preserved state of monumental buildings such as the Vittoriano, the “Palazzo delle Assicurazioni Generali”, the “Palazzo Venezia”, the “Chiesa di S. Maria di Loreto”, the “Chiesa di S. Marco”, the “Basilica Ulpia” and the “Auditoria di Adriano”, with the consequent drafting of “Testimoniali di Stato” (State Witnesses of Consistency) and the identification of interventions to safeguard any structural criticality detected;
- topographical monitoring activities of the same monuments;
- archaeological investigations in the underground area of “Piazza Venezia”, “Piazza Madonna di Loreto” and of the “Via dei Fori Imperiali” adjacent to the same (about 80 recovery corings until reaching a depth of about 15-20 metres-to the layers not affected by the anthropic activities of the past);
- investigations aimed at assessing the quality of the main atmospheric and environmental elements (air, groundwater, noise and vibration levels) in the area;
- geognostic investigations aimed at characterising the geomechanical behaviour of the different lithologies constituting the subsoil, and therefore predicting their behaviour in response to possible construction methods, mainly consisting of:
- A deep drilling campaign (of about 85 metres from the ground floor) functional to the execution of geotechnical tests and the installation of instrumentation.
- A series of field tests aimed at determining the efficiency of different methods of soil treatment, such as chemical cementitious injecting and freezing.
A campaign of environmental, structural, archaeological and geognostic surveys and investigations is in progress
In order to minimize as much as possible its impact on a context such as the “Piazza Venezia”, which is characterized, among other things, by intense vehicular traffic, tourist flows and institutional activities, it was deemed appropriate:
- To immediately establish a synergic collaboration with the Superintendencies responsible for the protection and management of the various monuments to be investigated, as well as the protection of the subsoil. This collaboration has made it possible to implement, with the help of primary Technical Studies and with the support of important companies specializing in archaeological investigations and conserving restoration a tight schedule of the study of the structural and preserved state of the buildings, as well as the archaeological coring in the subsoil;
- Immediately deploy 6 drilling rigs, each with its own working groups, in “mobile” construction sites, with “slender” fencing, to render it possible to remove immediately as soon as the specific investigation is completed;
- To create a more stable construction site in the southern part of the central flowerbed in Piazza Venezia, where the freezing and test field treatments can be carried out by means of chemical cementitious injections of the soil. This is because, by their very nature, they require a longer execution time and large equipment and installations.
FREEZING AND SOIL TREATMENT TEST FIELDS
The method of artificial soil freezing is a simultaneous waterproofing and/or consolidation technique for undergroundwater excavation. It consists of freezing water inside a volume of soil by circulating a liquid at low temperature, which extracts the heat and dissipates it outside. The freezing technique represents the most appropriate choice, particularly when operating in urban areas, in order to guarantee the highest possible level of safety, both for the workers involved and for the pre-existing surfaces. The project plans the installation of 21 vertical freezer probes with a length of about 65 m, and 12 thermometric probes necessary to verify the achievement of the ice thickness intended.