Issues on the seismic performance of embankments

Seismic vulnerability of embankments with reinforcement at their base is strongly related to the slip displacements, which may accumulate along the interface between soil and geosynthetic. The inertial accelerations within the embankment, due to the propagation of seismic waves and the subsequent dynamic response, are substantially altered by the inclusion of the geosynthetic.

Thus, geotechnical engineers should consider this crucial issue to ensure the integrity of the whole system and particularly of the geosynthetic. In the current study, two-dimensional dynamic parametric analyses have been performed. The stability of the soil mass was estimated in terms of seismic slip deformations along low-shear-strength interfaces, while the response of the embankment is assessed through the acceleration time histories at the top surface of the soil.

This investigation presents also the effect of the most significant parameters addressed in the literature affecting the dynamic response, namely the eigenperiod of the structure, the excitation’s characteristics and the shear strength of failure surfaces. The results of the dynamic response analyses indicate that the basic factors influencing the pattern of permanent displacement and the amplification of the ground motion are the ratio of the shear strength of the interface to the maximum applied acceleration as well as the tuning ratio of the geostructure.

Moreover, as the slip displacements were found to be suitably normalized by the maximum applied acceleration and the square of the period of the applied motion, the amplification levels and the frequency content of the response provided also consistent results. Nonetheless, since amplification levels may receive values much bigger than unity depending on the aforementioned factors, they shouldn’t be neglected during the seismic design of embankments.