Discrete element modeling of non-uniform biocementation in sand

The non-uniform distribution of CaCO 3 crystals is a ubiquitous phenomenon in biocementation, and is recognized as a critical factor influencing its mechanical performances. However, the non-uniform biocementation has not been thoroughly investigated due to challenges in quantitatively controlling the uniformity in experiments. In this study, we employ a 3D Discrete Element Method (DEM) approach to model non-uniform biocementation, using cementing fines to represent the CaCO 3 crystals. We generate two typical distribution patterns often encountered in element-scale biocemented specimens at varying degrees of non-uniformity to assess their effects on mechanical responses. The uniform specimen exhibits the best performance, followed by those with a cemented hull. Specimens with axial non-uniformity show the greatest sensitivity to the degree of non-uniformity and the poorest mechanical performance. Failure in the specimens with axial non-uniformity tends to localize in the weakly-cemented layers, while the uniform specimen and those with a cemented hull typically develop clear shear bands that cut through the specimens. Additionally, the evolution of the force chain network and contact-based anisotropy further emphasizes the role of weakly-cemented regions in the failure process. This study quantitatively examines the influences of non-uniform biocementation and provides valuable insights for element-scale experiments and practical applications of biocementation techniques.