Oct 24, 2014 | Rubrica Tunnel

Client: UTE Autovía Gerediaga – Elorrio

Place: Albadiño (Bizkaia)

Status: In cut-and-cover tunnel phase (25% of the work)

Estimated conclusion time: 2015

Project Coordinator: David Tichell

Identified needs: This is a formwork for the lining both of the bored tunnel and the cut-and-cover tunnel. In both cases, along the tunnel route, there are areas where the tunnel section expands laterally sidings).The cut-and-cover tunnel would be carried out in two phases; the first one with the concreting of the cut-and-cover tunnel itself, through the inner-outer formwork and a larger bored inner section than that of the tunnel; and afterwards, the cut-and-cover tunnel would be lined in order to achieve the same finish and section as that of the bored tunnel.

Why our solution? The tunnel had two sections with different radii that needed concreting (the cut-and-cover tunnel and the bored tunnel.) We recommended using one single formwork for both sections, suggesting a geometry that would adapt itself to both sections with a few minimal deviations with respect to the theoretical project section. Thus, with the same formwork, we have been able to carry out two different sections.

For the expansion or siding area, a telescopic transport cart was designed that would allow the opening of the formwork with a hydraulic system, in order to subsequently assemble a special piece or large width on the formwork, with the project-required width.

Description of the construction work process

  1. In the first phase, the footings or walls where the formwork will settle on and will be anchored to, shall be carried out.
  2. Afterwards, the cut-and-cover tunnel is carried out using both the outer and inner formwork.
  3. Next, the inner lining of the cut-and-cover tunnel is installed.
  4. Once all the cut-and-cover tunnel works are finished, we shall enter the bored tunnel, where the footings and walls have previously been carried out, and we go on to the concreting of the tunnel’s inner lining.