Performance of geosynthetic-reinforced pile-supported embankment on soft marine deposit

This study presents field investigations of a geosynthetic-reinforced pile-supported embankment for a transformer substation constructed on a soft marine deposit. The tests were performed following three procedures: construction, surcharge loading and consolidation. The soil stress, the accumulative settlement and the excess pore pressure at different locations in the field were monitored. The results indicated that, with the construction height increasing, the excess pore pressure caused by pile installations in the foundation soil decreased slightly and the pile-subsoil differential settlement increased insignificantly. When the differential settlement was relatively small, the soil arching effect developed rapidly as the differential settlement increased, also showing a partially mobilised characteristic. This partially mobilised arching was weakened under surcharge loading. During the consolidation procedure, the excess pore pressure dissipated remarkably, leading to a noticeable increase in the differential settlement. When sufficient differential settlement was reached, the partially mobilised soil arching developed to the fully mobilised state. At this state, the load-sharing ratio or the pile efficacy (ratio of load borne by the pile cap to the total load) remained steady. Furthermore, for the fully mobilised arching, the pile efficacy was well predicted by four analytical models.