First, the concrete drilled piles have been produced. Subsequently, Vroom Betonbouw started to produce 500 mm concrete pile heads allowing the entire station to be elevated, a private requirement. After that, the complete foundation has been delivered and applied in four mounting stages.
Construction team
The new station will be built on the site of the Frederikkazerne in The Hague and will become an accommodation for officers and flag officers. The design was made by the design team consisting of Heijmans Utiliteitsbouw, Burgers Ergon, architect agency Broek Bakema and construction agency Arcadis, advice from consultancy agency DGMR and Nieman and Heijmans Servicebouw for maintenance. Based on the starting points that have been outlined, a compact building measuring around 17,000 m2 has been designed: a functional army building including facilities and an integrated guardroom overlooking the future main port of the station. The selected design will result into less maintenance costs and less material costs. A central entrance and the application of footbridges have lead to optimal runlines. He guardroom is an integral part of the army building, but the specific front side shows it off as a separate part.
Bearing capacity building excavation
Before the project was kicked off, Vroom has checked the bearing capacity of the building excavation. On several locations, the site has been checked for water. As a result of the advice given by us, the soil has been improved on the site. In addition, sand has been applied on the site in order to get a flat site and to get to the correct working level.
Facilities
The foundation includes several facilities for utilities and the body on top. Because of the enormous pressure, the foundation elements will be tied to each other through wet knots. With her own dimensioning service, Vroom has realized the dimensioning process until detail for the foundation piles and foundations.
Routing and planning
The routing and the total execution period were of great interest for this project. The planning process started from the beginning of the production process of the foundation piles and Vroom needed 10 weeks maximum for the completion of the total foundation construction. Routing played a great role in this project as the floors and the concrete body on top had to fit the activities by Vroom seamlessly. For the construction process, the station has been divided into construction parts named IA, IB, IIA, IIB and III.
Foundation piles
First, the pickets have been placed by Vroom Dimensioning Service for the construction of part IA. Subsequently, a start has been made with the production process of the concrete drilled piles. Under ideal weather circumstances and in a well-bearing sandy building excavation, concrete drilled piles have been produced by Vroom. During this process, the piles have been finished off well at height on a level of pile heads to be applied in a later stage.
Pile heads
Given the ultimate use of the station, for the greater part, the upper side of the ground floor will be placed 1,4 m above ground level. To realize this without applying soil, for this part pile heads between the produced piles and the prefab foundation beams have been placed. Before the start of the project, the Vroom team has produced temporary timber shields for the pile heads. Once the first session of the 80 foundation piles had been hardened enough, the shields have been adjusted on a horizontal as well as the vertical level. Subsequently, the reinforcement baskets have been applied to the pile head shields. In addition, the rebar was included connecting the foundation to the pile head. In five sessions, the pile heads have been poured exactly at height.
Foundation construction
The required seamless connection of the ground floors and the body on top to the foundation beams had to be realized quickly. Already during the production process of the concrete drilled piles, the prefab process was started. During the production process of the heavy prefab foundation elements with several pouring options, much attention was paid to inserting these elements to size. The body to be applied on top of the foundation consisted completely of prefab concrete elements. These elements have to be able to be adjusted to size exactly whereas the connection to the foundation is established through rebars. The rebars with several thicknesses of Ø16mm, Ø20mm and Ø25mm were being placed at a maximum of 1,5 above the foundation. The adjustment tolerance of the rebars in the walls was nil which meant that at the factory during the production process of the prefab foundation elements, much attention was paid to exactly inserting them to size.
Wet knots
After applying the foundation of construction part IA, several elements have been mounted above ground level, not founded on piles. These parts have been mounted on a temporary supporting element and have subsequently been poured into the connecting beans through a wet knot. All poured rebars for the body on top have been checked for the correct position during the mounting process. Afterwards, the mounting process of the prefab foundation was finished. Subsequently, during this construction part the shields have been applied for the wet knots, ultimately allowing all foundation elements to be connected to each other. Then all shields and supporting elements have been removed resulting into the entire part to be founded above ground level.
Foundation blocks and elevator well
After this, construction parts IB and IIA followed. Inside construction part IB was a foundation block measuring 10,4 x 13,65 x 0,6 m. This one had to be isolated and poured. In construction part IIA the bottom part of the foundation ended up in front of a tunnel on 1,4 m below ground level. This foundation has been constructively calculated for colliding facilities in relation the chance for collisions where concrete columns are being connected. In construction part II, 2-pile foundation blocks were still present for a footbridge 0,9 under ground level. These foundation blocks have been equipped with DEMU anchors for a connection to the steel construction. This construction part also includes a 15,4 ton elevator well.
Facts & numbers project 33151 & 53486
New housing project Frederikkazerne
Location Van der Burchlaan The Hague
Contractor Heijmans Utiliteitsbouw Rotterdam
Client Dienst Vastgoed Defensie
Architect Broekbakema Rotterdam (Artist impressions)
Constructor Arcadis Rotterdam
Foundation piles concrete drilled piles
Number of piles 439
Diameter 500 mm
Pile length 8,40 m
Foundation specifications: traditional pile heads
Number of pile heads: 406
Dimensions WxLxH: 600 x 600 x 500 mm
Traditional foundation block
Number of foundation blocks: 1
Dimensions WxLxH: 10400 x 13650 x 600 mm
Traditional wet knot
Number of wet knots: 96
Dimensions WxLxH: 400 x 600 x 620 mm
Prefab foundation beams
Number of foundation beams: 901
Dimensions: 400 x 600 mm; 550 x 600 mm; 600 x 600 mm; 600 x 800 mm
Prefab 2-pile foundation blocks
Number of foundation blocks: 7 Dimensions: 400 x 600 x 2000 mm
Prefab elevator well
Number of elevator wells: 1
Dimensions: 2400 x 3300 x 1368 mm
Pouring facilities
DEMU anchors for connections: 868 M16, M20, M24, M30
Openings for utilities: 336 Ø75, Ø100, Ø160 and Ø200 mm
Rebars for prefab walls: 469 Ø16, Ø20 en Ø25 mm with a maximum length of 1615 mm
