Presentations

Abstract

The proper design and operation of scour protection systems is essential to prevent geotechnical failure and avoid variations in the vibration modes of bottom fixed offshore structures. Several formulations have been proposed in recent years for designing loose rock scour protection around monopile foundations. However, when it comes to more complex foundation geometries, such as offshore substations, the available literature is quite limited and, for certain types, non-existent. Given this lack of knowledge, the main focus of this study is the evaluation of the performance of rock scour protection systems for complex jacket structures composed of several pile clusters. This type of foundation is often used for offshore substations. The external stability of the rock protection was evaluated through several reduced scale physical experiments carried out at the IHCantabria facilities. For that, four jacket offshore substations were analysed under different co-directional wave and current conditions.  The experimental results showed different deformation patterns in the rock scour protection around different structural elements of the jacket foundations. Furthermore, the physical experiment results also showed a clear correlation between the maximum deformation measured and the magnitude of the undisturbed mobility parameter at the top of the scour protection.  Additionally, based on the data base generated, a predictive model was developed to estimate the scour protection deformation around mud mats as a function of the undisturbed mobility parameter. The model developed can be used as an engineering tool in order to design the external stability of the scour protection from the concept design of the foundations.