In geotechnical engineering, strain localization is commonly observed in slopes, foundations, and underground excavations. It often governs the onset of failure and post-peak behavior in soils and rocks. Classical plasticity models, although successful in describing the overall stress‒strain response, are inherently local and unable to simulate the initiation and propagation of localized deformation zones without encountering mesh dependency or numerical instability. The emergence of shear bands is rooted in the micromechanical characteristics of geomaterials, such as particle rotation, contact force chains, and fabric anisotropy. These features are typically beyond the resolution of classical continuum models. In parallel, field-scale engineering problems demand efficient numerical simulations via finite element methods. Bridging the microscale and macroscale requires not only a fundamental understanding of particle-scale mechanisms but also robust and physically consistent constitutive models that can regularize localization without artificial numerical artifacts. Recent advances in discrete element modeling, non-local continuum theory, and gradient-enhanced plasticity provide promising avenues for tackling these challenges.