Land reclamation for the Airbus A380 site on extremely soft soils in the "Mühlenberger Loch" within the River Elbe
Type:
Presented during:
WODCON XVII: "Dredging in a Sensitive Environment" - 2004, Hamburg, Germany
Authors:
J. Reiner, R. Stadie
Abstract: This paper presents a special approach to a complicated dredging problem, e.g. reclamation for an (heavy) industrial worksite on top of a thick layer of extremely soft subsoil. To be successful in the completion of this type of contract a thorough preparation, monitoring, guidance and supervision supported by a substantial contribution of geo-technical specialists is essential.
The Airbus site in Hamburg Finkenwerder is enlarged by an area of about 160 ha, which is taken from the "Mühlenberger Loch" for the production of the new Airbus A380. Along the area a 2.4 km long dike has to be installed for flood protection. The land reclamation was carried out by dredging about 11 Mio. m3 of sand into the basin, which were taken from different parts of the Elbe estuary and the North sea.
The project is especially governed by the very ambitious time schedule and the extremely weak subsoil conditions. On the basis of the provisional approval of the planning in August 2000 the works on site started in April 2001. Airplane production commenced in 2003 and the first A380 will be delivered to the costumer in early 2006.
The land reclamation in the "Mühlenberger Loch" has to be carried out on extremely soft organic silt layers, which have a thickness up to 12 m. To reach the very limited requirements of stability and settlement for the aircraft production area, it was primarily necessary to withdraw the reclamation area from the tidal regime by an outer dam (the later dike). The enclosed area was retained with about 3 m of water. Then the first thin sandlayers could be build up on the mud under the buyancy of water and the use of specially developed methods of sand - spreading and - spraying. Having reached the water surface the soil improvement was started under high efforts using vertical drainage, preloads or partly vacuum consolidation. The whole project was implemented on the basis of engineering analysis and prognosis and it is intensely reviewed by means of a geotechnical measurement system, which is supervised by a specially installed Geotechnical Management. The data from the measurements are used to control the different steps of the works in order to meet the requirements. On the basis of the actual status of measurement, the predicted residual settlement of about 15 to 30 cm within 5 years after handing over of the partial areas will be met.
Keywords: land reclamation, tidal regime, silt, soft subsoil, spreading, vertical drainage, vacuum consolidation, geotechnical measurements