A finite-element-informed Cerruti-based layered method for horizontal displacement of anchorage foundations with circular lateral confinement

This study develops a finite-element-informed layered correction method for estimating the horizontal displacement of anchorage foundations under circular lateral confinement. A Cerruti-based model is first established to calculate unconfined stress and displacement fields and is verified against PLAXIS 3D results. Idealized cylindrical confinement boundaries are then introduced to investigate the effects of confinement radius and horizontal load on shear-stress redistribution and foundation displacement. An area-based normalized stress-transfer coefficient is used to identify the onset depth of sustained stress attenuation and the corresponding equivalent diffusion angle. Based on this characteristic depth, a layered correction is formulated using the interlayer displacement difference between the foundation axis and the confinement position in the unconfined reference field. Results show that circular confinement enhances shallow stress redistribution, reduces downward stress transmission, and decreases horizontal displacement. The equivalent diffusion angles are generally close to 45°. For the investigated cases with R c / a ≥ 1.4, the relative differences remain within 6.82%, whereas markedly larger discrepancies occur under stronger confinement; additional predictive cases at R c / a = 1.50 and 1.80 give differences of 3.26% and 2.68%, respectively. The method provides a simplified framework for preliminary displacement assessment of large anchorage foundations under idealized circular confinement.