Tunnel Boring Machine “Iron-Erna” has wrecked – Technical Magazine

In January 2014 started the tunnel boring machine Iron Erna drilling of the 7.2 km long intake tunnel for new power station in Hemnes municipality in Nordland.

Now the machine, which was baptized by the contractor stalled dependent on new machine parts from Germany to get going again.

Heavy equipment

Tunnel Boring Machine now stands three kilometers into the mountains between Vesterli and Fallforsen.

Deputy Project Manager Geir Magne Svendsen Statkraft says it is not so easy to change parts of the machine on which it stands.

– The weight of bearing to be replaced is on 21 tons. It has a diameter of 5.2 meters, so it is not just simply to put in place a new one, he said.

To get to and replace the damaged section must it blasted a hole in the roof of the tunnel behind the tunnel boring machine.

There should be mounted hoists, which can lift out the old main warehouse.

– When it is done, the machine moves backwards so we can get inserted the new section, says Svendsen.

repair time is estimated seven to eight weeks.

Read also: Why not run major Norwegian road tunnels with tunnel boring machine

drill head to be replaced weighs 21 tons and has a diameter of 5.2 meters. Photo: Bjørn Grane

Many advantages

Technical Magazine wrote earlier this week that tunnel boring machines are not used for any of the major Norwegian road projects.

It is still not the first time this kind of problems arising from the use of tunnel boring machines.

But construction manager Erik Dahl Johansen explains that the benefits of using TBM are many, and the repair time is not so long that it affects project noteworthy.

– By choosing tunnel boring machine rather than conventional drilling and blasting, we can make a smaller tunnel. On the way, we get less masses to deposit, and we must spend less time and money on security. Furthermore we release to establish a adits on the middle of the tunnel, it had to have had if the tunnel should be driven with conventional operation, he said.

Johansen says that Norway was previously seen as a pioneer when it came to use of TBM in hard rock.

– It is far from a new method to use in Norway, but in recent years it has not been long enough force tunnels that it has been chosen, he said.

Read also: Eight tunnelborere will provide the biggest railway development since World War

The casualty will probably lead to a delay of eight weeks. Photo: Bjorn Grane

Too little knowledge about TBM

The projects that are particularly suitable for driving with TBM is namely the long tunnels. The method is much faster than conventional driving and reduces the need for both security and ventilation.

Johansen find it odd that the method is not used more in Norway.

– Conventional driving and TBM is perceived by many as two competing methods. That is incorrect. We are talking about two completely different methods, with different advantages and disadvantages. TBM can enable solutions for projects, and even to trigger some projects that would not be appropriate with conventional driving, he said.

And adding that lack of knowledge is probably the reason that the method used in so small degree.

– Both developers and consultants in Norway know enough TBM-drilling and opportunities and benefits that are there. It provides all too often reflected in the projects designed for conventional driving while contractors are invited to submit alternative offer with TBM. Should possibilities by TBM-drilling utilized method must be considered at an early stage in the project, he said.

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