Effects of Cementation Fabric on the Mechanical Behaviour of Bio‐Cemented Sands: Two Cementing Approaches in DEM Simulations

Bio‐cementation methods such as microbially induced carbonate precipitation (MICP) enhance soil strength through calcite precipitation, yet the influence of cementation fabric, defined as the directional distribution of cemented bonds, on mechanical behaviour has remained largely unexplored, despite experimental evidence that calcite can develop preferential orientations. This study provides a systematic investigation of cementation fabric in bio‐cemented sands using the discrete element method (DEM), and, in doing so, the first quantitative comparison of the two established DEM cementing approaches, namely virtual bonds and cohesive fines, within a unified framework. Specimens with four principal cementation orientations (i.e., , , , ) are prepared at an equivalent cementation level to isolate the effect of cementation fabric. Results demonstrate that cementation fabric significantly influences the mechanical behaviour: the specimen with a principal cementation orientation perpendicular to the loading direction achieves the maximum strength enhancement, while the one aligned with the loading direction exhibits the smallest strength enhancement. Furthermore, while the two cementing approaches yield consistent macroscopic mechanical behaviour, microscopic variables (e.g., coordination number and fabric anisotropy) vary significantly, resulting in approach‐specific interpretations of micromechanical mechanisms. This indicates that the choice of DEM cementing approach should be carefully considered based on the specific research objectives, such as the development of fabric evolution laws and micromechanics‐based constitutive models for bio‐cemented granular soils.