Thesis defence M. Barciela Rial: Marker Wadden

28 October 2019 15:00 - Location: Aula, TU Delft - By: webredactie

Consolidation and drying of slurries. A building with nature study for the Marker Wadden. Promotor 1: J.C. Winterwerp (CiTG); Promotor 2: Prof.dr. J. Griffioen (U-Utrecht).

The Marker Wadden project aims to improve the ecosystem of Lake Markermeer (The Netherlands) by constructing a wetland with sediment from the lake. This is dredged from the bed and the resulting slurries are pumped into the project area. During this process, segregation and oxidation may occur. The native sediment composition and changes therein induced by the construction process affect the mechanical behavior of the wetland. Next to this, the initial stress state of the sediment is another variable determining the behavior. At a later stage, vegetation may colonize the wetland, influencing the mechanical properties of the sediment as well. These aspects were studied in this thesis with physical and numerical experiments. The general conclusion is that over-consolidated initial conditions can be induced by different processes such as mixing and atmospheric drying. Furthermore, the composition of the sediment may change when exposed to segregation and oxidation. In particular, the type of organic matter affects the mechanical behavior of fine sediment at all stages (settling, consolidation, drying) and needs to be characterized. These aspects have traditionally been disregarded in engineering practice. However, the present research shows that they affect the mechanical behavior and need to be addressed in the design phase of a project using fine sediment as construction material. Herein, the material parameters need to be determined for the actual project conditions. Furthermore, in this design phase, a decision has to be made to allow or prevent the formation of a saturated crust, which affects the final strength and thickness of the bed. Preventing the formation of a crust allows to achieve the maximum bearing capacity. As a counterpart, the sediment surface is then less strong and more sensitive to erosion.

More information?

For access to theses by the PhD students you can have a look in TU Delft Repository, the digital storage of publications of TU Delft. Theses will be available within a few weeks after the actual thesis defence.