Metrostav last month holed through on the drill and blast drive for the second Icelandic state-funded road project undertaken by the Czech contractor.
The 6.9km long drive for the Olafsfjordur tunnel began in November 2006 and the contractor has bored through difficult geology with high groundwater pressures and inflows.
Geology along the alignment in the Trollaskagi peninsula is basalt and sedimentary interbeds, and of widely varying competency. Overburden was 5m-600m.
Although relatively little groundwater was met early on, the drive was to later encounter pressures up to 32 bar, and although there was risk of thermal waters the temperatures found were 2 degrees centigrade. Approximately 630 tonne of chemical grout was required.
The entire excavated length for the tunnel will be approximately 7.1km, including open cuts at each the portals. The cross section is 52.83m2 (Norwegian profile T8.5) though it is larger at passing places, and the vertical alignment is a 3% incline for almost 5.45km downward and a 1.4km long stretch at 1% rise.
In September 2006, excavation of the first tunnel – Siglufjordur – began and Metrostav holed through to open air a year ago. The mined length was approximately 3.6km and open cuts of approximately 0.2km were excavated at each end.
Metrostav’s project director is Ermin Stehlik. The company is in a JV for the project with local firm Hafell, which is doing roads and bridges. Geotek is project supervisor.
The project is being undertaken by the Icelandic Road Administration – Vegagerdin – to reduce the travelling time, and weather complications, for vehicles between the towns of Siglufjordur and Olafsfjordur. Following completion of the 14km long new link the travel distance will be reduced from 60km though it is often far longer because of poor weather in the area (T&TI, September 2007, p6).
Olafsfjordur road tunnel bore finished in Iceland
