Metro Buenos Aires

As part of Buenos Aires City Metro master plan, the B Line Extension was executed, to the north of Villa Urquiza Terminal station. This extension project comprised a depot cavern, long enough to shelter four train formations, and a workshop tunnel, able to hold two formations for repairing.

About the project

The depot, with a 200 m² excavation cross section and a 20 m total width was one of Buenos Aires largest caverns by the time of its execution. The completion of the first 350 m civil works was a priority for the City Government, as it conditioned the inauguration of two new stations, Echeverría and Villa Urquiza.

Following the depot, the workshop was built, with a 130 m² cross section and a 14 m total width. Its alignment had it running below the 2nd Main Sewer, located close to the tunnel crown. Serious limitations to the allowable settlements were therefore a project condition, which led to a very complex constructive sequence engineering.

Advantage of using NATM for the detailed design

The detailed design included sophisticated geotechnical numerical analysis models, following the New Austrian Tunnelling Method (NATM). This models were continuously adjusted for a better on-site representation according to the work progress, allowing optimization of the construction procedures, consequentially guaranteeing an optimal economic and technical design, while also maintaining an adequate safety level.

Monitoring the soil behaviour

On site soil behaviour was verified by a thorough monitoring program designed and executed directly by GC GROUP which included 3D cavity displacement monitoring, establishing a new standard for the Buenos Aires Metro Line construction works.

On the basis of the monitoring results and cavern geotechnical stability analysis performed during construction, the construction sequence was adjusted in order to improve economic conditions on the contractor’s side.