Centrifuge modelling of piled bridge abutments on soft ground

Piled bridge abutments on soft clay may be loaded laterally from horizontal soil movements generated by the approach embankment. A limited number of field trials have been described in the literature, although the data are generally limited in extent, complicated by variations in geometry or soil conditions, or of relatively poor quality. This paper presents the results of a series of centrifuge model tests aimed at clarifying the behaviour of piled bridge abutments on soft clay. The centrifuge modelling techniques and equipment used are initially described. Attention is focused on the induced pile bending moments and deflections, and the response is shown to be critically dependent on the factor of safety of the embankment against failure. The effects of variations in pile rake, embankment geometry and abutment wall loading are described. The response of pile groups with time after embankment construction is outlined and the causes of time dependent behaviour identified.