Suction Installation Envelopes for Caissons in Loose Stratified Offshore Seabeds

Abstract

The rapid global expansion of offshore renewable energy infrastructure has driven the need for reliable, cost-effective, and efficient foundation solutions. Suction caissons have emerged as a highly viable alternative to traditional driven piles due to their rapid installation, minimal noise emissions, and reversibility for decommissioning. However, their installation in loose stratified offshore seabeds presents complex geotechnical challenges, including the risk of premature refusal, excessive soil plug heave, and piping. This paper presents a comprehensive investigation into the development of suction installation envelopes for caissons penetrating through loose stratified soil profiles, specifically alternating layers of loose sand and soft clay. Through a rigorous combination of physical centrifuge modeling and advanced large-deformation finite element analysis, the research delineates the critical boundaries that define safe and successful installation trajectories. The study identifies the complex hydro-mechanical interactions that occur at the interface of distinct soil strata, highlighting how seepage forces and localized shear failure mechanisms interact to govern penetration resistance. The findings indicate that stratification significantly alters the required suction pressure and the allowable suction limits compared to homogeneous soil profiles. By synthesizing the experimental and numerical data, the paper proposes robust installation envelopes that provide critical predictive guidelines for offshore geotechnical engineers. These envelopes serve as a practical tool for optimizing installation procedures, ensuring structural integrity, and mitigating the risks associated with complex seabed conditions.