Numerical Analysis of the Performance of a Hybrid Anchorage Foundation for Long-Span Suspension Bridges

Abstract

The hybrid caisson–steel tubular pile group anchorage (CSTPGA) provides an optimized anchorage foundation solution for long-span suspension bridges. In this study, three-dimensional finite element analyses were carried out to investigate the performance of the CSTPGA under the main cable tension. The numerical modeling method was first validated against experimental data from a model test. A comprehensive parametric study was subsequently conducted to evaluate the effects of pile diameter, pile spacing, pile length, and soil stiffness on the displacements of the CSTPGA, as well as the deflection and internal force responses of the critical corner pile Pc. The results indicate that increasing pile diameter significantly enhances the pile group’s load-sharing ratio within the CSTPGA. Furthermore, the mechanical performance of the CSTPGA is improved by increasing pile spacing and length. However, the CSTPGA may not be suitable for sites characterized by excessively soft soil conditions. In addition, embedding pile toes through the sandy silty clay into the underlying stiff cobble stratum markedly enhances axial load mobilization and fixes the elevation of the peak positive bending moment at −56.81 m, which corresponds to the geological interface between the two soil layers.