ABSTRACT
The paper describes relevant design aspects for the extension of Torino Metro Line 1, work that includes a double track circular single tunnel (total length equal to 1733 m), two underground stations (Bengasi and Italia ’61-Palazzo Regione), three shafts (PB22, PB23 and P24). The tunnel, 6.88 m in (internal) diameter, has been excavated by using an EPB TBM, with the contemporary disposition of a precast lining composed by 5+1 r. c. segments, 1.4 m long and 0.3 m thick. Intervention area is strongly urbanized, reasons why working choices and procedures have been defined to obtain an adequate level of robustness, also taking into account the difficult underground scenario, extremely heterogeneous and in presence of water. Technological aspects and particular solutions are discussed and described. In detail, the effect of the design choices about the definition of the correct TBM confinement pressure on the tunnel face is analyzed, by comparing settlement predictions and monitoring results.
