Zalmhaven, Rotterdam | Zalmhaven I founded to great depth

The foundation of high-rise tower Zalmhaven I was not driven, but drilled because the piles had to be driven about 66 meters into the ground, through load-bearing sand layers up to a sand layer from the Pleistocene. Silent and vibration-free drilling is then an obvious solution. The tower will soon stand on 163 soil displacement Tubex piles with welded drilling tips. The chosen solution has been extensively tested.

The Tubex pile is a further development of the Fundex pile, developed at the time by the Zeeuws-Vlaanderen-based Funderingstechnieken Verstraeten BV, among other things for the renovation of the Amsterdam Concertgebouw. Managing Director Ed Revoort: "The Zalmhaven I involves complicated soil conditions in combination with high-rise buildings. The concentrated loads on a building postage stamp called for a customized solution and that is what the Tubex pile provides, which allows us to drill to great depths through dense soil layers."

Two segments

First of all, the first segment of the hollow steel pile is brought to depth, with a welded drilling tip fitted with special teeth to penetrate possible obstacles. This segment reaches a depth of about 29 meters below sea level and is filled with concrete. Then, at ground level, the second segment is welded on and provided with a grout mixture (cement with special binders) further at depth to more than 65 meters below NAP. Revoort: "The work was carried out in-house from late October 2018 to March 2019 with two Fundex drilling rigs and at a rate of about 10 piles per working week. During winter conditions, the drilling crews braved the cold."

Third-party review

Tubex^‌-piles are more commonly used for high-rise buildings above 70 meters; however, additional meticulous project supervision and necessary review was performed. Revoort: "Because of the height of Zalmhaven I and the associated risk control, a so-called CC3 test was required, in which an independent, qualified third party tested the chosen foundation solution. The work was also extensively probed, including a full scale test bore. We can say after completion of the work that the process met our expectations, based on 163 Tubex piles with a bearing capacity of 1,200-1,600 tons per pile."