Micro–Macro Assessment of the Pile Bearing Capacity Interaction with Single and Double Voids in Different Soil Densities Using the Discrete-Element Method

Abstract

This study focuses on how soil's inherent variability, driven by environmental changes, introduces substantial uncertainty into geotechnical considerations. Voids forming underground are a key source of this uncertainty, affecting subsoil structures like piles. Using a two-dimensional discrete-element method and considering both fundamental (micro) and engineering (macro) approaches, this study investigates the influence of voids in sandy soil on a pile’s behavior, especially on the pile’s bearing capacity and lateral pressure coefficient acting upon its shaft. The results reveal a critical zone around the pile where voids can dramatically reduce the pile’s bearing capacity, with load reductions of up to 63% in the most extreme cases. Surprisingly, voids have a minimal impact on the lateral pressure coefficient along the pile wall. Thus, it is deduced that the primary cause of the pile’s load reduction in the presence of the void is the decreased resistance at the pile's tip. In summary, this research underscores how voids in sandy soil significantly affect the bearing capacity of piles, emphasizing the importance of understanding these effects for safe and efficient subsoil structure design in geotechnical engineering.