The ground investigations for the fixed Fehmarnbelt link, which began in the summer, will now continue on land.
Over the coming months, experts will carry out geoelectrical measurements with relatively light equipment on the island of Fehmarn. Together with the previous seismic investigations, the results of the subsurface investigations will provide a better understanding of the local geology – i.e. the location of the different soil layers.
It is crucial for the future Fehmarnbelt project that engineers have accurate and detailed knowledge of the soil layers upon which the structure will be founded. The result of the ground investigations will also contribute significantly to the final selection of the link’s alignment.
Femern Bælt A/S, the company responsible for the fixed link, plans to conduct the ground investigations in stages over the next four years. Initially, the plans are to obtain a general understanding of the local geology and then to go into further detail in line with the project’s ongoing development.
Methods and implementation for each step will, therefore, build on the results from the previous stage. This means that all investigations can be carried out with the minimum of inconvenience for plot owners and that the number of subsequent test drillings will be limited.
The current geoelectrical measurements will not lead to any lasting impact on the surroundings. In cases where the geotechnicians have to pass through or work in, e.g. planted fields, compensation will be paid in accordance with current regulations. By way of a personal letter, Femern Bælt A/S has informed the ten owners on whose land the measurements on Fehmarn will be conducted.
Geoelectrical investigations will not be carried out on Lolland. This is partly owing to the fact that soil conditions on Fehmarn are more complex than those on Lolland and partly because comprehensive investigations of soil conditions have already been conducted on the Danish side.
The geoelectrical measurements on Fehmarn will begin after November 16. The measurements will be carried out on the soil surface with two current electrodes linked by a cable. The electrodes will send a weak current through the soil which will enable the geotechnicians to measure differences in potential at selected points between the two electrodes and thus determine the electrical resistance in the various soil layers. As the electrical resistance varies between the different geological layers, this will determine the soil layers’ condition to a depth of 120 meters.
The measurements will be carried out in Germany along five lines, each of which are 2 km long. A single measurement on one line may extend up to 800 metres and will typically last for 2-4 hours. Afterwards, the measuring equipment will be moved down the line ready for the next measurement.
The investigations will be conducted by a consultancy group responsible for the geological/geotechnical investigations on behalf of Femern Bælt A/S. The group consists of Rambøll Danmark A/S (DK) and Ove Arup & Partners Ltd. (UK).
Based on the results from the autumn, the geotechnicians expect to identify five-six locations in Germany and another five-six in Denmark where test drillings will be carried out from May 2009. The drilling will last for one week at each location.
When the results from the drillings become available in 2009, Femern Bælt A/S will identify an area of approx. 2,000 m2 for larger-scale field tests. Over a couple of weeks, 20-30 m long steel piles will be driven into the earth after which measuring equipment will be put in place. Over the next three to four years, this equipment will provide detailed information about the soil layers. Experiments using concrete plates, which will be loaded in different ways, may also be undertaken.
The field trials will reveal whether the subsoil will be able to bear the huge weight of the future structure without any damaging settlements and to what extent it will be necessary to introduce piles extending deep into the subsoil.
The ground investigations are expected to cost around Euro 40 million.
For further information, please contact Project Manager Jens Kammer, Femern Bælt A/S, tel.: + 45 33 41 63 09.
Femern Bælt A/S is a 100 per cent publicly owned limited company under Denmark’s Ministry of Transport. The company is tasked with carrying out the initial investigations and other preparations for the construction of a fixed link across Fehmarnbelt between Denmark and Germany.
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