The nonlinear behaviour of pile group foundations subjected to earthquake loading involves several varied phenomena such as soil-pile interaction, pile-raft interaction, soil nonlinearities and pile damaging. To accurately account for these phenomena, a significant number of degrees of freedom are required, especially close to the contact zone between the pile and the soil. This research proposes a novel two-phase model formulated within the framework of a macroelement to take into account the soil-pile interaction. The proposed macro-element uses a multi-scale substructuring approach based on FEM. Each macro-element represents a single-pile and its immediately surrounding soil. The macro-element is an assembly of twophase elements based on two independent meshes for the pile and for the soil. Interface forces between the pile and the soil are integrated continuously on the interface length with an ad hoc interface constitutive model. The focus of the paper is the presentation of 1D and 2D two-phase elements. Test cases with both linear and nonlinear interface laws are shown to validate the elements.