Full-scale model tests of load transfer in geogrid-reinforced and floating pile-supported embankments: Fid-Bau Portal

Full-scale model tests of load transfer in geogrid-reinforced and floating pile-supported embankments

Zhang, Chonglei / Su, Lijun / Jiang, Guanlu

Abstract Well-designed field full-scale model tests were carried out to enhance the understanding of geogrid-reinforced and floating pile-supported (GRFPS) embankments constructed on medium compressibility soil (MCS). Two comparative test sections of GRFPS embankments with and without pile caps were built over silty clay with medium compressibility for field monitoring, over 25 months. The heavily instrumented embankments produced comprehensive high-quality data. Settlement, earth pressure, and geogrid strain measurements during embankment filling stages and the postconstruction placement stage were conducted. The influence of pile cap installation on the differential deformation and load transfer behaviour of the GRFPS embankment was evaluated. The results demonstrate the installation of pile caps can significantly improve the evolution characteristics of the stress increment ratio on the pile, facilitating a change in load sharing of the pile top from a “softening” feature to a “hardening” feature. The state of the “arching structure” heavily depends on the relative displacement. After the maximum arching is formed, although the subgrade load continuously increases, the arching enters the damage and recovery state, and the transfer of the overburden load increment is largely conducted by the tensioned membrane effect.

Highlights • Well-designed field full-scale model tests were carried out to enhance understanding of the GRFPS embankments. • Installation of pile cap significantly affects the horizontal distribution characteristics of settlement and earth pressure. • Phases of the development, formation, damage and adjustment of the soil arching structure were defined. • Evolution of stress increment ratio and stress reduction ratio showed how basal reinforcement affected soil arching. • Pile efficiency and stress concentration ratio were applied to investigate load transfer efficiency of GRFPS embankment.