TUNNELLING WORK on the Portugal's Oporto metro, halted in January following a ground collapse in which a woman died, is due to restart within weeks.
Since the collapse engineers from Reading-based Jacobs Gibb has been drafted in as consultant to client Metro do Oporto. The project was originally due for completion in 2004.
Work stopped with only around 300m of the 5.7km bore completed on the $782M design, build and operate scheme after a two storey house between the Campanha and Heroismo districts collapsed weeks after the tunnel boring machine had passed under the dwelling.
There was no structural damage in the completed tunnel bore.
Contractor is the Normetro consortium including Soares de Costa, Adtranz, ABB, SAE, Somague, Impregilo, Transdev and Semaly. Austrian consultant Geoconsult is acting as a subconsultant to the consortium.
Findings from a number of inquiries including a government investigation, have not yet been released.
Ground conditions are difficult. Soil is granitic, but ranges from solid granite rock to loose and soft material, with granite content between 50% and 90%.
'There are lots of problems in tunnelling with this type of soil, which can differ greatly over very short distances, ' said Metro do Oporto spokesman Nuno Ortego.
The contractor is using an 8.71m diameter Herrenknecht earth pressure balance TBM.
A new management structure has been imposed, bringing closer involvement of the client with the supervision of the work.