Interfacial behaviour of Expanded Polystyrene (EPS) geofoam in embankments: a review of numerical approaches

Since the 1970s, Expanded polystyrene (EPS) geofoam has been widely utilised as a lightweight fill material in the construction of road or railway embankments over soft ground. In such projects, EPS geofoam is typically installed as stacked blocks, resulting in direct contact between individual blocks and adjacent construction materials. The effective design and implementation of these composite systems require a thorough understanding and consideration of both the shear behaviour of EPS geofoam and the interfacial behaviour between EPS blocks and surrounding soil or structural elements. Accordingly, this paper initially presents a comprehensive review of existing experimental investigations into the interfacial properties of EPS geofoam, identifying key factors that influence its behaviour. Subsequently, available numerical analyses of EPS-filled embankments on soft ground are discussed, with a focus on the findings, assumptions, and limitations inherent in these studies. Notably, most of these numerical models treat the EPS fill as a continuum, overlooking the discrete nature of block arrangements and their interfacial effects. Consequently, this review highlights a significant gap in current modelling approaches: the lack of consideration for interfacial properties and block-scale interactions in numerical simulations. Understanding the influence of misaligned or improperly placed blocks is essential for accurately assessing the stability and performance of EPS-filled embankments. The findings underscore the need for more refined modelling techniques that incorporate the blocky nature of EPS geofoam and its interactions with surrounding materials.