How is finite element analysis applied in geotechnical engineering?

Geotechnical FEA models soil using constitutive models: linear elastic (limited use), Mohr-Coulomb (basic plasticity), Hardening Soil (stress-dependent stiffness), Soft Soil (creep), or advanced models (Hypoplastic, MIT-S1). Applications include deep excavations with sequential construction, embankments on soft soil with consolidation coupling, tunneling with ground loss simulation, and soil-structure interaction. Challenges: mesh dependency for localization, parameter selection, initial stress state, and validation. Software includes PLAXIS, FLAC, and ABAQUS with geotechnical modules.