A methodology to evaluate the changes of undrained shear strength in the sub-soil as a function of time under the centreline of an embankment was developed. This is based on model simulations, using the instrumented test embankment in Haarajoki, Finland, as a case study. The simulations demonstrate that the evolution of the undrained strength under embankment loading as a function of time is complicated. Firstly, the evolution of strength is related to both consolidation and creep, which are strongly affected by the apparent preconsolidation pressure and the creep parameters. Any significant gains in strength are only possible when the effective stresses go beyond the normal consolidation surface. Furthermore, the degradation of bonding in sensitive clays may in the short term reduce the undrained shear strength, in particular if the preconsolidation pressure is only marginally exceeded. Most importantly, the results also identify gaps in our knowledge, with regards of the role of the evolution and anisotropy and principal stress rotation on the evolving undrained shear strength, which affect the strength mobilisation in most of the failure surface.