The stability of an embankment on soft soil is governed mostly by the shearing resistance of the foundation and it is most critical during and at the end of construction.
This is because the relatively low permeability of the soft clay does not permit significant drainage and consolidation in the time scale of the construction.
The application of reinforcement to an embankment over soft soil is a relatively short-term application, within a structure with a long design life. The role of the reinforcement (high strength) then, is to maintain the stability until such time as the soft foundation soil has consolidated (and gained in shear strength) to the degree that it can support the weight of the embankment itself.
The reinforcement will act to reduce the forces causing failure – by carring the outward shear stresses generated by the embankment fill. And also increases the forces resisting failure – by providing inward shear stresses on the surface foundation.
