Numerical simulation of scale effects in shallow soil anchors interacting with shear bands

Abstract The interaction between geotechnical structures and plastic shear zones influences the performance of these systems, particularly in case of nonstandard installations with miniaturized components. This paper examines this problem numerically with an implicit gradient-enhanced plasticity model able to constrain the shear band thickness dictated by the soil microstructure. The model, therefore, enables the quantification of scale effects regulated by differences between system dimensions and interacting shear zone geometry. The effectiveness of the model is demonstrated by examining the pullout capacity scaling of miniaturized shallow plate anchors. The numerical simulations, validated by 1 g experiments, show that decreasing model size leads to an increase in pullout capacity across all levels of anchor uplift, along with thickening and shortening of the corresponding shear bands. Such effects are amplified by anchor burial depth and are also observed in centrifuge tests and corresponding simulations, provided that the model setup involves variations in the relative dimensions between particles and the tested geostructure. Finally, corrective factors are introduced based on the shear band thickness to anchor size ratio, thus facilitating the quantification of the pullout capacity for anchors with nonstandard geometry and miniaturized components, for which such scale effects are expected to be more prominent.