Excavation and support of two tunnels. Tunnel No. 1 of 380 m, highly complex, excavated on highly altered siliceous schists and mylonites. The section oscillated between 128 and148 m2. The whole tunnel was perforated below successive micropile shields, with central abutment and placement of HEB-180 trusses spaced at 0.60 to 1m apart. Tunnel No. 2 is a conventional blasted tunnel of 480 m of micaceous and clayey schist, with an excavation section of 125 m².
