Numerical investigations into the drainage effects on the behaviors of plate anchors under unidirectional and combined loadings

This study presents one of the first systematic investigations into the drainage-dependent behaviors of a deeply embedded plate anchor under unidirectional and combined loadings using finite element analysis. The hydro-mechanical soil response is modeled via Biot’s consolidation theory coupled with the Modified Cam-Clay model, incorporating a regularization scheme to address numerical instability near the drained regime and to robustly capture anchor–soil detachment. Results show that anchor capacities are strongly dependent on drainage conditions and are predominantly governed by the normal component under combined loading. Failure mechanisms vary significantly with drainage and are generally localized around the anchor, except in drained penetration, which induces notable mudline settlement. Detachment at the anchor–soil interface arises under near-drained conditions across all loading paths and progressively vanishes with increasing loading rate due to the mobilization of interfacial suction. A typical transition from detachment to attachment is observed near a dimensionless velocity of V = 1. A quantitative method is proposed to identify threshold velocities separating drained, partially drained, and undrained regimes. Both thresholds are identified for various unidirectional and combined loading paths and exhibit strong path dependency, attributed to differences in pore pressure generation and dissipation mechanisms across loading scenarios.