The navigation in ports and waterways has to be safeguarded by maintenance dredging, removing sediments deposited by tide, river flow and waves. These deposits consist of soft, fluid-like sediments, referred to as fluid mud characterized by low density and weak shear strengths. As dredging of fluid mud is highly in-efficient, port authorities seek for conditions at which ships can sail through fluid mud, leaving the deposited sediments in place. Thus a new definition of “nautical bottom” within the fluid mud layer has to be considered globally. Due to practical reasons, the density of the fluid mud has been used as a key parameter to define the nautical bottom. However, it has long been recognized that a practical definition of nautical bottom should be based on considerations not only of density, but should also include the viscosity and yield stresses of the mud (the so-called rheological properties of the sediment-fluid mixture. Moreover, it has been found that rheological properties depend on the stress history. This feature of mud is known as thixotropy. To get better understanding of the rheological behavior of fluid mud a new insight into the subject can be obtained from the rheological analysis of mud samples from different ports, i.e. the Port of Rotterdam, the Port of Delfzijl, the Port of Emden, the Port of IJmuiden and the Port of Zeebrugge. The yield stress, dynamic viscosity and thixotropy of mud, rheological experiments can be experimentally captured in the laboratory. The thixotropy of cohesive sediments can be predicted by various rheological models. These models can be utilized to bridge the maritime activities (such as navigation and dredging) to the alterations of rheological properties of fluid mud in different ports and waterways.
The first goal of this project is to obtain a new practical under-
standing of fluid mud thixotropy taking into account the physical parameters that might influence the rheological properties of the fluid mud layer. The rheological parameters should be linked to the properties of mud and, as representation for the shear history, to the maritime activities.
Supervisors: Alex Kirichek (TU Delft),
Claire Chassagne (TU Delft),
Tiedo Vellinga (TU Delft/Port of Rotterdam),
Arie Noordijk (Port of Rotterdam)
The second goal of this work is to conduct a laboratory analysis of the rheological properties of mud samples from different ports in order and to explain the differences in rheological behaviour of mud types. The following research questions can be covered during the project:
• What is the impact of navigation and dredging activities on rheological properties of fluid mud?
• How the thixotropy of fluid mud can be linked to the ship navigation and dredging?
• What models are suitable for predicting the rheological properties of mud?
• What is the difference between mud types from different ports in terms of rheological signature?
This project is fully sponsored by the Port of Rotterdam. The student is expected to start working on this project on the 6th of March 2017. The deadline for applications is the 4th of December.
For more information please contact:
Alex Kirichek O.Kirichek@tudelft.nl CiTG room: S3.00.100 (Water Lab).
Claire Chassagne C.Chassagne@tudelft.nl CiTG room: S3.00.080 (Water Lab).
Tiedo Vellinga T.Vellinga@tudelft.nl CiTG room 3.83.