Axisymmetric transient modelling of a suction caisson in sand: a numerical study

This paper deals with the axisymmetric behaviour of a suction caisson installed in sand upon vertical monotonic and cyclic loading. A steel caisson is numerically modelled using the finite element code LAGAMINE. The Prevost model reproduces the cyclic behaviour of the soil, i.e. it captures the accumulation of deformation and pore water pressure within the soil. Coupled interface finite elements allow the modelling of the uplift behaviour of the caisson in both drained and partially drained conditions. Upon compression or traction loading, the suction caisson presents different modes of resistance: friction along the shaft, bearing capacity under the lid or the tip of the caisson, suction effect. The first part of this work describes the progressive mobilisation of these modes of resistance during monotonic simulations. The partially drained effect is particularly interesting since it drastically increases the resistance to transient loading. It proceeds from the transient consolidation process induced by the caissons loading. The second part describes the evolution of the settlement of the suction caisson upon different kind of cyclic loading signals.