A modified suction caisson penetrating in clay simulated by large deformation method

Suction foundations, which are widely used in marine engineering for their cost-effectiveness and reusability, have evolved into modified suction caissons (MSCs) incorporating an internal caisson (IC) and an external skirt (ES). A clear understanding of their penetration behavior is essential to ensure successful installation. In this study, the coupled Eulerian-Lagrangian (CEL) method is employed to simulate MSC penetration in clay, with particular emphasis on soil flow behavior, heave formation, and variation in penetration resistance. The influence of foundation geometry, friction coefficient, and soil properties on penetration performance is systematically examined. Results show that the length-diameter ratio of the IC significantly affects the caisson's ability to reach the target depth. An increase in ES length alters the heave distribution, resulting in greater soil heave on the outside compared to the inside of the caisson. Variations in ES width notably alter soil flow patterns. While soil properties exert a stronger influence on end resistance than the friction coefficient, the increase of undrained shear strength (su) reduces the slope of the soil heave profile within the caisson. These insights provide a foundation for optimizing MSC design and installation in clay soil conditions.