Speaker
Description
The presentation will focus on the development and application of a new medium-scale shear rig to investigate the interaction between subsea linear infrastructure and the soil to support the offshore energy sector. The rig incorporates a representative pipe or cable segment that can be subjected to axial or longitudinal shearing against a wide range of seabed conditions, spanning from fine granular soils to coarse, cobble dominated seabeds.
The initial development of the rig was aimed at investigating the axial friction behaviour of polypropylene coated pipelines in contact with various seabed materials under low stress conditions. Extensive validation was conducted through direct comparison with small scale direct shear box tests in sands. The experimental programme was subsequently extended to granular materials with particle sizes ranging from sand to gravel, cobbles, and analogue rocky seabed conditions.
In response to evolving industrial needs, the rig was further developed to study the lateral interaction between electrical cable protection systems (CPS) and scour protection for offshore wind turbines. The upgraded rig allows testing of full scale CPS specimens (up to 40 cm in diameter and approximately 1 m in length) placed over realistic rock armour used in scour protection systems. Large cumulative displacements over repeated cycles are imposed to simulate operational lifetime conditions, enabling assessment of the evolution of resistance forces acting on the cable protection system, and abrasion of the CPS over its service life.