By Ashley Karen
Earlier this month, a tunnel boring machine excavating Line 2 of the Lima to Callao Metro project in Peru broke through into a station.
The TBM is called Micaela and is 10.27m in diameter. It broke through into Buenos Aires Station after tunnelling 1km from Juan Pablo II station in less than two months.
So far, the machine has bored slightly more than 2km of the tunnel on the project since starting its journey at Insurgentes Station in the Callao district of Lima last year.
The Webuild Group is providing the $3bn (£2.2M) civil works for the metro project in consortium with local and European partners.
The Line 2 construction will contain building 27km of the tunnel to link Ate and Callao districts of Lima and building a section of another scheduled metro line called Line 4. These two new lines for the city’s metro system will enhance mobility across the city which is one of the most crowded in the world.
Micaela and Delia (a second TBM) will bore the tunnels and build 35 stations, 36 ventilation and emergency shafts and two train depots for Line 2.
Micaela tunnel boring machine can bore over 1000m3 of earth and rock daily. It pulls the material from the face to clear the tunnel and then places the concrete segments that make up the rings, which are the final lining of the tunnel. Each ring contains six regular-size voussoirs and a small one that serves as a closure.
For building the tunnel between Juan Pablo II and Buenos Aires stations, the tunnel boring machine placed 588 rings, each weighing 40t and advanced between 15m and 20m per day.
The recent breakthrough comes a year after the first section of the Lima metro project completion, once the Delia tunnel boring machine broke through into the future Circunvalación Station.
