The factory, which will produce the 79 standard elements for the Fehmarn tunnel, consists of three halls, one of which is close to completion.
Right now, the last offal is being installed. This concerns electricity, air conditioning, scaffolding and the final moulds for the two motorway pipes.
Nine segments per element
A tunnel element of 217 meters consists of a total of nine segments of approximately 24 meters each. The tunnel element will be 42 meters wide and nine meters high and weigh 73,500 tonnes.
Each casting of the concrete segments that make up the tunnel contains approximately 450 tonnes of reinforcing steel, which must be precisely tied together to give the tunnel its strength.
Trial castings
Two trial castings have been made to prepare for production, which has provided valuable knowledge.
– We have cast a full-size railway pipe in two rounds, where the height and width are the same sizes as the future railway pipe must be, but only half the length. The trial castings have taught us that in addition to having the right temperature when casting, you also have to have the right temperature in the long pipes that the cement runs in before it is pumped into the construction, otherwise, you can get unevenness in the concrete, explains Jens Ole Kaslund, technical director at Femern A/S.
Practicing handover
Casting takes place over 36 hours, so it is not the same people who are with you all the way. It is, therefore, important to prepare for how the handover will take place.
– They get to practice that with the test castings so that it only works when they have to get down to business with the real castings, says Jens Ole Kaslund.
Concrete more fluid
With the trial castings, the correct concrete composition has also been found.
– In the second trial casting, the concrete had been made more fluid than it was the first time so that it is now both fluid enough and strong enough, concludes Jens Ole Kaslund from Femern A/S.
In January, the casting of the first segments will begin, and during 2023 the first complete tunnel element will be ready.
