Non-linearity in the seismic design of reinforced earth.

The use of geosynthetic reinforced structures in seismic areas is becoming very widespread, being these structures able to store large deformations without collapsing. This research refers the results of some numerical modelling of steep geosynthetic reinforced embankments subjected to different earthquakes. Depending on the degree of internal and external fixity steep reinforced embankments may have two types of failures: the internal failure and the external failure. The aptitude of the reinforced earth to slide was verified with the displacement method outlined by Newmark and founded on the dynamic equilibrium of a sliding block provided of a Coulomb friction. Only the direct sliding mechanism was investigated by considering the critical acceleration that was evaluated with limit equilibrium and limit analysis. By comparing the FEM seismic results with the pseudo-static previsions, a reduction factor of the peak ground acceleration of the design earthquake was outlined, with the purpose of introducing the ductile behaviour of the structure within the pseudo-static approach.