DFI Europe Member Report: “Sluishuis” Amsterdam, an Extraordinary Landmark In Amsterdam, Netherlands, about 20 min. from the city center, Van ’t Hek is constructing the foundation for the iconic Amsterdam Sluishuis, an extraordinary landmark, which wi l l house 442 luxurious apartments (73 for sale and 369 for rent). Its construction, when finished, will allow pleasure crafts to navigate into a patio-like courtyard and moor to the building’s jetties. The project is being developed and constructed by Besix and Vorm and will be completed by spring 2022. Because the building has to rise from the “Buiten IJ” Lake, its shape induces a complicated play of actions on its foundation, which is a challenging assignment for the piling company and geotechnical engineers. The building cantilevers over one side, which forms the entrance from the water. This means that in an ultimate limit state (ULS) situation, the foundation rafts on the other side of the building will be subject to tension forces, while the concentrated load on the cantilever construction requires a pile tip level of about 63 m (207 ft) below reference level. be driven with the pile top to about 5.50 m (18 ft) below the water and silt levels. The precast piles will be installed using silenced hydraulic impact hammers to reduce noise emission and nuisance for the neighbouring residential area, IJburg, as much as possible. There will be 102 precast piles within the two tension rafts and will have a maximum load of about 900 tonne (992 ton). Due to the concentration of load on a small area, the design engineers and geotechnical engineers decided that these piles could not have their tip level within the second Pleistocene sand layer, in which most piling works in that area are installed. These piles had to pass the second Pleistocene sand layer and the so called “eem clay” to have the pile tips at a depth of about 63 m (207 ft) below reference level, well in the third sand layer. Driving these piles with an impact hammer would cause a lot of nuisance and even impose a high risk for damaging neighbouring structures. This is why the piles will be installed as steel screw piles using a 50 tonne-m (361,774 ft- lb) rotary head. The lost steel casings have a diameter of 864 mm (34 in) and a thickness of 11 mm (0.43 in), with a lost conical drill head of 990 mm (39 in) in diameter. The piles are installed in two segments, which are welded together after installing the first segment of 30 m (98 ft). After the installation of the 800 precast concrete piles is Architectural rendering of the Amsterdam Sluishuis, the jetty view This loading condition causes a very interesting piling layout, consisting of 714 precast concrete piles varying in length between 15.5 and 17.5 m (51 and 57.5 ft), which will Installation of the piling from barges complete, Van ’t Hek’s job is not done. Around the perimeter of the building’s footprint, a double cofferdam of steel sheet piles will be installed. Between the two sheet pile walls, a sand fill will be placed to create a surrounding construction site and roads, while the inner area will be dredged and drained to create the building’s foundation and two-story parking basement. Later in the construction phase, Van ’t Hek will return to extract the sheet piles, since these piles are not part of the permanent structure. 52 • DEEP FOUNDATIONS • MAR/APR 2019
