Cross-Comparison of Plastic Hardening Models in FLAC3D and PLAXIS3D for Soil Behavior Simulation

In the evolving field of geotechnical engineering, numerical modeling is a fundamental tool for understanding soil behavior. The selection of an appropriate constitutive model is pivotal for accurately representing soil behavior and ensuring the reliability of analyses conducted through finite element (FEM) or finite-volume methods (FVM). In this study, the elasto-plastic behavior of soils under drained and undrained conditions is simulated using two widely used software programs, FLAC3D (FVM-based) and PLAXIS3D (FEM-based), to replicate triaxial laboratory results obtained from these soil types. The results of this study showed that utilizing the Mohr-Coulomb model for both undrained and drained cases yielded consistent results between FLAC3D and PLAXIS3D. Good agreement was also observed between the stress–strain plots generated by both software programs under drained conditions when using soil Plastic Hardening constitutive model. However, for undrained conditions, discrepancies were observed, with PLAXIS3D showing a lower CU shear behavior compared to FLAC3D at similar strain levels. The potential causes of these observed differences are discussed.