GETINSA - Complementary studies for the section Requejo – Padornelo of the Madrid – Galicia high speed railway line. Section length: 18.9 km
The project consists in lowering the invert of the existing Padornelo Tunnel and reinforcing the tunnel support. It covers the termination of the invert that will support the track concrete slab, which is not included in the project. The line referred to in the contract is part of the North-Northwest high speed corridor between Zamora and Lubián.
The line alignment is determined by the use of the existing tunnel, since the route for the new line will run along the tunnel axis. On the other hand, the need to increase the tunnel clearance required to lower the track height. The design involves the construction of a single-track line on concrete slab, to minimize the necessity to lower the invert, although the superstructure is not included in the project as it was mentioned before.
The tunnel has a total length of 5,990 m, resulting from the expansion of the tunnel section and the demolition and reconstruction of the artificial tunnels to adjust them to the terrain. As for the artificial tunnels, the one at the entrance is 16 m long, and the exit one totals 22 m long. There will be cross passages (10 m long) within a parallel tube on the right side of the tunnel. It is classified as a Level 1 tunnel, due to its length and low traffic flow (these are tunnels of a particular nature that require a specific and permanent organization for the control and monitoring of facilities).
As the project design speed is 350 km/h, the tunnel cross-section must be of at least 52 m2. It will consist of a sidewalk of variable width depending on the track cant, which involves a 30-cm-wide ditch for drainage purposes and a foot walk totaling at least 1.20 m of width and with a 2.25 m clearance. This sidewalk is 35 m high over the rail and works as an evacuation route.
With respect to the construction method, a central trench was initially excavated. Then, with the aid of a temporary support structure where it was necessary to reinforce the invert, side walls’ area was lowered and strengthened and concrete was poured on said invert.