This paper describes a study performed to evaluate the seismic behaviour of a 10 m high bridge end sand fill placed upon soft organic foundation soils and supported on piles. Under static conditions the fill load is essentially carried by the piles by arching action , and little deformation was observed to occur in the field. The results of both model tests and finite element analysis are in agreement with this finding. Concern arose as to the likely response of this structure under earthquake loading and a model sand embankment supported on 400 model piles was built and tested on the shake table. The model and testing procedures are described in some detail in the paper. The results of the shaking table study indicate that during shaking the load is transferred from the piles onto the foundation resulting in large deformations of the fill. Analysis of the model tests based on this assumption gave deformations that were in good agreement with observed settlements. A similar analysis of the prototype indicates that seismic loading sufficient to cause such transfer would result in a settlement of the fill of about 0.4m, and that deformation would cease once the shaking stopped
