ABSTRACT
Behaviour of offshore foundations such as piles or bucket foundations is highly dependent on interface properties. Shear mobilisation along their boundaries is crucial, not only under tension but also lateral loading. Gap opening plays an important role to develop the suction effect under bucket foundations.
Offshore foundation behaviour is often computed in purely drained (long-term) or undrained (short-term) conditions. However, dissipation of over-/under-water pressures may dissipate fast especially in sand. Subsequently in some cases the true behaviour is not purely drained nor purely undrained, but partially drained.
We developed a hydro-mechanically coupled finite element of interface able to reproduce loss of contact, friction mobilisation (Coulomb criterion), sliding, water flow along the interface and through it. Hydro-mechanical couplings arise from the definition of an effective stress, the dependence of longitudinal flow and storage to gap opening.
A bucket foundation is modelled upon lateral loading to illustrate the capabilities of the finite elements as well as the effects of couplings on the overall caisson behaviour.
