Performance comparison of capped pile and piled beam support systems for embankments on soft soils

Geographical locations with soft soil present significant challenges for constructing transportation earthworks due to the soil’s high compressibility and low shear strength. Pile-supported embankments are a proven solution; however, the relative performance of different pile–cap–beam configurations under equal area coverage ratio (ACR) conditions remains insufficiently quantified. This study investigates the hydromechanical behavior of soft soils improved using Capped Pile Supported Embankment (CPSE) and Piled Beam Supported Embankment (PBSE) systems through fully coupled three-dimensional numerical analyses calibrated against field data. The models incorporate geosynthetic-reinforced cushion layers and examine basal pressures, excess pore pressures, settlements, lateral displacements, and pile/beam deformation patterns. Results show that, at equal ACR, CPSE transfers vertical loads more directly to piles, reducing centerline settlement, whereas PBSE provides greater lateral restraint, reducing horizontal movement at the slope toe. Parametric analyses for embankments of 5 m and 10 m height reveal that PBSE generally offers higher stability, with optimal ACR ranges depending on embankment height. These findings provide a controlled baseline for performance comparison and inform future optimization, including considerations for traffic-induced bending, cyclic loading, and seismic effects.