Investigation on the Behavior of Stiffened Caisson Installation in Uniform Clay from Large Deformation Modeling

Suction caissons, widely applied in offshore engineering, suffer from significant uncertainties about the flow mechanism of the surrounding soil during installation, especially for caissons with ring stiffeners. Large deformation finite element (LDFE) analyses are carried out to investigate the behavior of stiffened caisson by visualizing the soil flow mechanism during the caisson penetration. The LDFE method was first validated against centrifuge test data and good agreement was obtained. A systematic and detailed parametric study was then conducted by considering a large variety of parameters, including stiffened caisson geometry, interface friction coefficient, and soil shear strength. The results show that the ratio of caisson diameter to stiffener width and the normalized soil strength has a significant influence on the soil flow mechanisms. The definitions of critical rotational soil flow depth (Hr) and the limiting cavity depth (Hc) were employed to quantitatively describe the behavior of the observed soil flow mechanisms. An equation was developed to describe the maximum height of the inside soil heave. Prediction of the total penetration resistance was described with a simplified flow mechanism around stiffened caisson based on the observed LDFE results.