Goal
Offshore structures (foundations, cables, pipelines, jacket footings) often experience scour at the interface with the seabed. The (local) erosion of sediment results in a lowering seabed level. This can -among others- result in a reduction of the lateral load capacity of foundations, free spanning of line-infrastructure and a reduction of the fatigue life (FLS). To prevent this, a scour protection is typically applied. Large cost saving can be achieved by selecting the most suitable scour protection system for each application, and/or by optimizing the scour protection design.
To that end, Deltares has teamed up with the corporate sector and other top research institutes to launch a Joint Industry Project: JIP Handbook Scour and cable PROtection (JIP HaSPro). In JIP HaSPro a generic, science-based and systematic comparison is made between different scour protection methods. This comparison is aimed at optimizing existing methods, testing new methods and providing recommendations/guidelines on when and where to apply which method. This comparison is based on a long model test programme performed in Deltares' facilities, the scale of which ranges from 1:50 to 1:1, including the world's largest wave flume "Delta flume".
Scour protection methods
In JIP HaSPRo we focus on three scour protection methods. First, conventional (loose) rock protection methods are considered against scour around monopile foundations or cable crossing failures. For these -relatively well understood methods- we focus on filling the gaps of available datasets. To assess these conventional protection methods we focus on all possible failure mechanisms, meaning both external and internal stability as well as flexibility of scour protections, conducting specified tests.
Furthermore within the JIP HaSPro scope, many innovative protection methods have been tested in experimental conditions, some of them for the first time, to provide us with alternative solutions to help reduce the costs by simplifying the installation phase, facilitate monopile decommissioning and finally protect against scour, infrastructure that is situated in highly dynamic environments where extreme morphological changes and hydrodynamic conditions are expected. Such innovative methods include concrete block mattresses, gabions, artificial vegetation, ballast-filled mattresses and self-installable systems.
Lastly, we focus on eco-friendly scour protection methods. Nature-inclusive design of scour protections is aimed at increasing the potential ecological value that wind farms may add to the marine environment, by providing shelter for target species or by contributing to restoration of previously booming reefs that have degraded while subjected to human pressures like in the North Sea. In JIP HaSPro we build an ecological framework that accounts for the existing legislation and guidelines and provides a consolidated basis for the offshore wind industry to make choices concerning all phases of nature-inclusive design. Furthermore, we test the hydraulic stability and overall performance of scour protections that include ecological elements like shells and reefballs.
Sponsors
Two TKI's:
TKI-WOZ
TKI-DT
21 participants
Main deliverables
The deliverables of the JIP HaSPro include new design formulae, an online digital handbook and an Engineering Software Tool for the considered scour protection methods in this Joint Industry Project. Moreover, a large database with model test results, containing 3D-data of scour protection layouts and deformation patterns, as well as a 3D-viewer to visualize these results are part of the deliverables of this JIP. Results will be confidential for a certain period which typically is 2 years.
Timeline
JIP HaSPro was initiated in 1-9-2016 and will be in progress until 1-9-2020.
