Parametric analysis of ground anchor geometry influence on the performance of CFA pile walls in layered soils

Abstract

Retaining structures based on continuous flight auger (CFA) pile walls with ground anchors are widely used in deep excavation projects in urban environments, where space constraints and the proximity of existing structures impose strict limitations on wall deformations and surface settlements. Despite their practical importance, the combined influence of anchor inclination and anchor length on the overall performance of CFA pile walls in layered soil conditions remains insufficiently studied in a systematic, parametric manner.
This paper presents a numerical parametric study investigating the effects of ground anchor geometry, specifically anchor inclination angle and free/fixed anchor length, on the bearing capacity, lateral displacements, and global stability of CFA pile retaining walls embedded in layered soils. A reference geotechnical model comprising representative alternating cohesive and cohesionless soil layers with a groundwater table above excavation level was established as the baseline configuration. Anchor inclination varied in the range of 10° to 30° from horizontal, while anchor length was varied across five discrete values representative of typical design practice. Numerical analyses were performed using the finite element method combined with strength reduction technique to evaluate the factor of safety, wall bending moment distribution, anchor force mobilization, and horizontal wall deflection for each parameter combination.
The results indicate that anchor inclination has a nonlinear influence on wall performance, with intermediate inclination angles yielding the most favorable combination of anchor force efficiency and global stability. The findings provide practical guidance for the preliminary design of anchored CFA pile walls and highlight the importance of accounting for soil stratification when optimizing anchor geometry.