MUNICIPIO STATION IN NAPLES: THE COMPLEX DESIGN OF TWO TUNNELS UNDER ARCHAEOLOGICAL REMNANTS.

ABSTRACT. The work deals with the design of two tunnels, currently under construction, connecting the existing Municipio Station access shaft, interchange node between Metro Line 6 and Metro Line 1 extension project in Naples (Italy), to the TBM extraction shaft located nearly 40 m far from it. The two short tunnels have to underpass archaeological remnants consisting in fortification walls built in the sixteenth century, through a subsoil composed by a loose silty sand overlying a soft and sometimes fractured rock (Neapolitan Yellow Tuff) and below the groundwater table. The design and the choice of the construction processes have been very complex, adopting a mix of different measures as cement and chemical grouting at the sides and inverts in tuff and Artificial Ground Freezing at the crowns in sand, together with the compensation grouting technique, even for the obvious needs to preserve a unique archaeological site, part of mankind's common heritage