An increasing number of offshore energy structures have been built recently on driven piles, ranging from jack-
et piles with typical length-to-diameter (L/D) ratios of 10-40 to monopiles with far lower L/D ratios. The load-displacement
behaviour of these foundations can be investigated by means of Finite Element (FE) analyses, for instance following the design
methodology developed by the PISA Joint Industry Project (JIP). A challenging aspect of the modelling, for piles loaded either
axially or laterally, is the simulation of the behaviour at the soil-pile interface with the adoption of suitable formulations for the
interface elements and with representative mechanical properties. This paper presents a sensitivity study conducted on both the
elastic and plastic properties of interface elements adopted in FE analyses of laterally loaded piles driven in chalk. The study
benefited from the extensive field and laboratory test results collected during the ALPACA JIP and the corresponding pile
tests. The aim of the paper is to provide guidance for numerical modelling on the selection of the most appropriate mechanical
properties of interface elements to be used in the analyses of soil-pile interaction under lateral loading.