Analysis of the ultimate uplift resistance and progressive failure process of strip plate anchors in marine sensitive clays: a FE analysis based on micropolar continuum theory

This study presents a Tresca-inscribed Mises micropolar continuum model for undrained marine sensitive clays, which simultaneously accounts for strength heterogeneity and nonlinear strain softening. The model incorporates the Tresca criterion to ensure an accurate representation of soil strength while leveraging the numerical convergence of the Von Mises model. Implemented within finite element analysis, the model demonstrates superior computational performance, effectively addressing severe mesh dependency issues in strain-softening soils. Validated against existing literature data, the model accurately predicts the ultimate pullout resistance of plate anchors, accounting for both strength heterogeneity and strain-softening behaviors. Parametric analyses reveal that strain-softening parameters have a significant impact on the uplift resistance factor N c , with reductions in the strain-softening coefficient ω and increases in the shape factor η leading to a decrease in N c . In contrast, strength heterogeneity, characterized by the gradient k, shows only a slight effect on N c . The paper also provides a table of N c for plate anchors in heterogeneous strain-softening soil at different depths, based on extensive calculations. This table covers common engineering scenarios and can help engineers to determine N c . Additionally, the study elucidates the progressive failure mechanism of soils during anchor uplift, revealing the evolution of equivalent plastic strain and undrained shear strength.