Author(s): W. C. D. Kortlever; A. Capel; I. Van Der Werf; P. L. M. Jansen; W. F. Louwersheimer; H. A. Verovoorn

Linked Author(s):

Keywords: Physical model; Hydraulic loads; Wave impacts; Flood gates; Discharge sluices

Abstract: To anticipate the rising sea level and to meet the increased flood safety standards the Afsluitdijk in the northwest of The Netherlands is currently being reconstructed. The Afsluitdijk is the dam, with a length of 30 km, that closes the IJsselmeer basin, the former Zuiderzee. Outside the dam lie the Waddenzee and the North Sea. The reconstruction of the dam includes the reinforcement of the dam and the raising of the crest level, the renovation of the existing discharge sluices and the building of new pumping stations, discharge sluices and flood gates. Higher design waves and water levels, including the effects of sea level rise, present determining loads for drawing up the strength and stability of these hydraulic structures. One of these loads is the wave impact load on the gates, supporting beams and bridge decks of the discharge sluices. At first, these loads have been calculated using a design approach which has been based on analytical models, only partially validated (Almeida and Hofland, 2020). It showed that these loads due to vertical wave impacts can be higher than the strength of the gates and the existing bridge decks. Therefore, load reduction measures are required. To better predict the wave impact loads, which strongly depend on the configuration of the gates and decks, a physical model study in a wave flume has been carried out at Deltares (Capel and van der Werf, 2023). This abstract is about the results of this model study, focusing on the wave impacts on the existing discharge sluices near Kornwerderzand, because at this location these loads are the highest. The physical model aimed at the determination of wave impact loads on the bridge decks, the cable duct and the gates of one of the channels of the discharge sluices. As the impact loads for wind waves coming from the Waddenzee had been derived from earlier model tests, this study considered extreme wind waves coming from the IJsselmeer. Figure 1 shows a typical cross-section of the discharge channels, showing the two gates, the North deck and the South deck, and the cable duct (Thijsse, 1972). The width of a discharge channel is 12 m and the decks are 7.15 m above the channel floor. The highest water level is NAP + 2 m (NAP: Amsterdam Ordnance Datum) and the channel floor is at NAP - 4.75 m. So, the maximum water depth is 6.75 m. The cable duct has a width of 2.1 m, and the North Deck and the South Deck have a width of 11.4 m and 11.0 m, respectively. The opening between the North Deck and the South Deck, with the South Gate open, was 1.6 m wide.

DOI: https://doi.org/10.59490/coastlab.2024.811

Year: 2024