Metro de Santiago is currently building Lines 3 and 6, which cover an area of roughly 37 kilometers (22 miles) across eleven districts of Santiago. Line 6 links Avenida Pedro Aguirre Cerda near the former Los Cerrillos Airport, to the planned station of Vitacurra in the munici- pality of the same name. The excavation and support of these tunnels are generally based on the use of the New Austrian Tunneling Method (NATM). However, there have been proposals to adjust the excavation and support methods in order to improve efficiency and lessen overall construction time. One alternative involves the so-called “Self-Supporting Vault” (SSV) method and includes the installation of a pipe arch umbrella as systematic pre-support. This option is envisioned for the construction of the station tunnels.
Metro Line 6 Constructability Review and Evaluation:
During early stages of the design, Gall Zeidler Consultants (GZ) was retained as an expert consultant to review and evaluate the constructability of the SSV method for Line 6, as well as a structural analysis of the inter-station tunnels. Further, GZ also performed an independent quantitative evaluation using 2D FEM analysis.
On 2015, GZ was retained as a technical advisor to support Metro during a contractor’s claim regarding the first two construction sub-sectors. GZ performed a review of the tunnel design, bid documentation, geotechnical information at the moment of the bid and the documentation of the contractor’s proposal and performance to assess the short-comings that the construction had and support the arbitration process