The TBM Dalia (110-meter-long and 1,280-ton weight) arrived from China a few months ago and has been assembled in the launch chamber and began excavatiosn for the Bisagno flood diversion tunnel in Genoa.
The TBM, in the weeks following its launch, installed the first ring composed of 8 precast reinforced-concrete segments, each weighing an average of 7.8 tons
Once the initial section of the tunnel lining was completed, the TBM was able to proceed with the support and reaction phase on the segments using 21 main hydraulic jacks, providing the thrust necessary for the cutterhead advancement.
At the same time, the transport systems for the spoil were activated, the front chamber was pressurized, and the continuous excavation and lining cycle began.
The completion of the alignment and support operations marks the beginning of the actual excavation of the 6.5 km tunnel toward the sea.
The TBM, once fully operational, will excavate at an average rate of 20 m/day until reaching the tunnel's adit, at Corso Italia. The excavated spoil is transported by truck to a storage area just upstream from the construction site for subsequent use according to the design specifications.
The general revision of the contract between the commissioner’s office and the temporary contracting consortium composed of Research Consorzio Stabile scarl of Naples (NA), Amec srl of Santa Venerina (CT), and Manelli Impresa srl of Monopoli (BA), is also progressing well. This will allow for a realignment of the project's completion schedule and ongoing updates until the end of the work.
The use of the closed-shield TBM is the result of an improvement variant approved by the contracting authority in August 2023: Dalia allows for the simultaneous, uninterrupted execution of excavation and placement of the precast lining segments.
This ensures both a reduction in tunnel completion times and improved safety conditions during construction. The project has a total cost of over EUR200 million and involves the construction of a tunnel connecting the Sciorba area with the sea in Corso Italia, diverting a significant portion of the Bisagno stream’s peak flow away from its riverbed.
The spillway system will work in conjunction with the smaller Fereggiano system, already operational since autumn 2019. Click here and it/216 for tunnebuilder archive. Visit https://www.scolmatorebisagno.it/ and https://www.regione.liguria.it/. 48/25.
