Penetration resistance of stiffened caissons in uniform and soft-over-stiff clays

The prediction of the penetration resistance of stiffened caisson involves uncertainties due to the complex soil failure mechanisms, which makes an obstacle for its application. In this paper, stiffened caisson installations in single-layer uniform and double-layer soft-over-stiff clays are investigated. Large deformation finite-element (LDFE) analyses are employed to simulate the caisson installation process. Soil flow mechanisms, especially inside the caisson along the inner stiffeners, and the caisson installation resistance are studied. Along the inner stiffeners, both soil/soil sliding and soil/skirt sliding mechanisms are observed based on the soil strength and caisson geometry, especially the stiffener geometry and spacing. During the caisson installation in soft-over-stiff clays, the soil flow mechanisms observed in the single layer uniform clay can be replicated in the top soft clay layer before the caisson penetrates into the bottom stiff clay. Caisson full installation resistance can be predicted based on the combined soil-flow mechanisms revealed in single- and double-layer uniform clays.