Evaluation of Anchor Axial Force Prediction Methods for Pile-Anchor Retaining Structures Based on Field Monitoring and FEM

Pile-anchor retaining systems represent a fundamental support technology for urban deep excavations, where accurate quantification of anchor axial force is essential to achieving both structural safety and economical design. Here, we systematically assessed the predictive performance of several established design approaches—namely the static equilibrium method, the equivalent beam method, the earth pressure envelope method, an empirical chart-based method, and the CPD method—against in-situ monitoring data acquired from a deep excavation project. Under the site-specific conditions, the chart-based method delivered the closest agreement with the measured anchor forces. We further implemented a finite element model to perform a parametric sensitivity analysis, elucidating the influence of anchor embedment depth, excavation depth, and groundwater table position on anchor axial force. The results revealed that increasing anchor embedment depth produced only a marginal variation in anchor force, indicating weak sensitivity. In contrast, deepening the excavation produced a pronounced escalation in anchor force and significantly modulated pile bending moments. Elevating the depth to the groundwater table (i.e., lowering the water level) caused the anchor force to decline monotonically, with the rate of decrease progressively attenuating at greater depths, thereby demonstrating a moderate dependency on groundwater conditions.