Presentations

Abstract

Pre-installed scour protection presents several challenges for the installation of (mono)piles through rock armor layers. In the offshore industry, there is still limited understanding of rock–structure interaction and the considerations required to ensure a safe pile installation in accordance with design specifications. While recent studies involving full-scale experiments and Discrete Element Modelling (DEM) have examined the penetration load needed to penetrate piles through scour protection, less attention has been given to the influence of the underlying soil layers on these predictions. This study addresses this knowledge gap by integrating the effects of both the pre-laid rock armor and the subsoil layer into the load transfer estimations during the self-weight penetration phase of a (mono)pile, while also accounting for the actual installation vessel response.   Real-world data from XXL monopile installations by a floating vessel offer valuable insights into the monopile (MP) installation process through rock armor layers. A sudden transition into a soft material or loose sediments beneath the rock armor can cause an abrupt drop in resistance, leading to a rock punch-through event. This incident arises when the monopile, still connected to the crane, accelerates suddenly at a rate the crane cannot match. Analyzed field data highlight the critical importance of having a robust, pre-established risk management strategy to mitigate potential damage to the installation equipment.   The findings of this study underline the need for developers and designers to factor in operational risks associated with rock punch-through events, as the consequences for installation equipment can be significant depending on the subsoil conditions. For offshore contractors, the results emphasize the need for location-specific evaluations of potential rock punch-through impacts. Overall, this study equips industry stakeholders with the knowledge to make informed decisions and mitigate risks when implementing pre-installed scour protection solutions.