Abstract

In offshore engineering, Subsea Rock Installation (SRI) is a cost-intensive process. This study focuses on a pipe-in-pipe project in the Norwegian Continental Shelf (NCS), addressing the challenges posed by a soft-clay seabed and deep iceberg scars. Traditional 2D limit equilibrium methods (LEM) often fail to capture the complex realities of these environments, particularly in terms of 3D seabed and rock geometry, and comprehensive material behavior. The rock volume based on 2D LEM design is also over conservative. Recognizing these limitations, this research advocates for the adoption of a 3D finite element method (FEM), which offers a more accurate analysis. By employing FEM, particularly for the stability of free-span infills in deep iceberg scars, it aims to optimize rock volume usage. The results suggest potential cost reductions up to 16%, underscoring the value of embracing more comprehensive design and simulation processes. These insights offer valuable guidance for future offshore engineering projects, paving the way for more efficient and confident design strategies.

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