Graduation of Casper Jantzen

28 oktober 2020 14:30 - Locatie: Lecture Hall G, Faculty of Civil Engineering and Geosciences & Online - Door: Webredactie

Experimental study of the influence of bed protections on scour depth and scour development in front of sloped embankments

  • Chair of graduation: Dr. ir. B. Hofland

  • Supervisors of graduation: ir. C. Kuiper (TU Delft), dr. ir. M. A. de Schipper (TU Delft), ir. W. J. Ockeloen (Van Oord) 

In front of coastal structures, which protect harbours, beaches and land, sediment movement takes place due to incoming waves. The erosion of sediments creates a scour hole at the toe of embankments, breakwaters and dikes. This scour hole can lead to instabilities of the main structure due to material sliding into this hole. A common method to protect against scour is the placement of a toe structure and a bed protection. In this thesis it is researched what the influence of a bed protection is on scour depth and scour development in time. Besides that, the influence of structure permeability and the hydraulic conditions is researched. This is done by performing physical small-scale model tests in the wave flume of the fluid dynamics laboratory of Civil Engineering. The data obtained from the tests is analysed to give relations between scour and the researched parameters.
The analysed data showed that the bed protection, directly influences the location of the scour hole. However, the maximum depth of the scour hole is barely influenced by the amount of bed protection. On the other hand, the permeability of the structure and the hydraulic conditions have large influences on the amount of scour. The data is also used to derive an equation, which estimates the scour depth development over time. A similar equation shows the scour pattern close to the coastal structure. With these equations engineers can better estimate the scour development when designing an embankment, a dike or a breakwater.