Development of drawings, measurements, etc. and execution of works for the reactivation of the Monte Olimpino Tunnel 2 between km 3+258 and 4+053 along the Milano – Chiasso railway line.

MAIN WORKS:

Complete restoration of the two-track railway tunnel of Monte Olimpino 2. Works can be divided into two macro-groups. The first macro-group concerned the re-profiling and waterproofing of the tunnel, including the consolidation of side walls through their hydro-demolition and successive lining. Then, the tunnel was consolidated in the connection point between the tunnel invert/side walls through cement and resin grouting. Later, the invert tunnel was lowered through milling. Moreover, tie-rods and consolidation micro-piles were created. Lastly, works were completed with the total redoing of the entire profile of the tunnel, by casting the invert tunnel and then the side walls and the arch thanks to mobile formwork specifically designed for the project. We dealt with the waterproofing of the tunnel with double membrane in polyolefin with vacuum injection system.

The second macro-group of works concerned, instead, the adjustment of the inner profile of the tunnel following a major sagging. Therefore, the entire section was demolished through the traditional mechanical excavation, followed by the installation of steel ribs and lastly by the creation of the covering through concrete casting.

Some of these works (consolidation and hydro-demolition, cutting and installation of reticular steel ribs) and the finishing works (installation of cable runs in reinforced concrete, cable installation, temporary lightning removal, permanent lightning installation) were done on the two-track section during railway traffic (out of hours).