Case study on feasibility and performance of embankment over soft soils with beam-type capped piles

Highway construction in mountainous areas with soft soils requires effective foundation treatment technologies for embankment performance. Rigid piles have been widely employed in highway and railway construction. However, some cases reveal the inadequate ability of rigid piles to resist horizontal loads, which highlights the significance of improved rigid pile-reinforced embankments. This study investigated the efficiency of a composite foundation reinforced with prestressed pipe piles connected by ground beams, focusing on the Wujiu highway. Field measurements involve contact pressures, settlement, and lateral displacements on piles and surrounding soil, thus assessing embankment stability during and after construction. Results show that significant control over total and differential settlement, with post-construction settlement being <12 % of the total, demonstrating swift stabilization. Lateral displacements were almost equivalent for the outermost pile and adjacent soil, with ground beams effectively limiting lateral deformation post-filling. The effect of soil streaming flow around piles that may occur in conventional pile-supported high embankments was not observed. The reinforcement system controlled vertical and horizontal deformations, enhancing the whole embankment stability. Ground beam responses varied across the embankment profile, with central beams bearing more load. This study underscores the pile-beam system's value in supporting embankments on soft soil, offering insights for similar geoengineering projects.