Role of geogrids in load transfer of pile-supported embankments

A series of physical model tests on a geosynthetic-reinforced pile-supported (GRPS) embankment were performed in the laboratory to investigate the role of a geogrid on the load transferred to the pile-supported embankment. Two geogrid types, which differ in tensile stiffness by a factor of 2, were used to study the effects of geogrid stiffness. Different embankment configurations having different total embankment heights were employed so as to allow a comparison of the effects of different relative settlements between the soft soil and the piles. From the test results, it was shown that the relative settlement between the soft soil and the piles is necessary to form soil arching. In particular, when the embankment was geogrid-reinforced, the additional vertical stress transferred to the piles by the reinforcement with the geogrid became significant only when this relative settlement was sufficiently allowed. Furthermore, a larger additional vertical stress transferred to the piles was achieved by reinforcement with a stiffer geogrid. However, the difference in the vertical stresses transferred to the piles was substantially smaller than the difference in the geogrid stiffness.