Back analysis of PISA pile tests at Dunkirk using a practical Nor-Sand model

It is typically challenging to model numerically soil-structure interaction problems in sandy soils with high ac-curacy. Difficulties include employing competent but practical soil constitutive models and dealing with issues associated with sample disturbance. In this paper, the Nor-Sand model is shown to be a promising candidate capable of overcoming these problems. The PISA pile tests performed at Dunkirk were selected as a case study. The ground conditions were reproduced by the Nor-sand model, and selected PISA lateral pile tests were back-analysed. A parametric study was performed by using both the parameters derived from laboratory tests on reconstituted samples and from in situ testing that captured the sand deposits’ long-term fabric and ageing effects. Recommendations are provided for achieving representative sand characterisation. It is empha-sised that for numerical modelling, the most important steps are careful characterisation and parameterisation of the soil model, rather than the numerical modelling per se.