Piled embankments utilizing geosynthetic reinforcement have become an accepted technique where it is necessary to maintain surface grade lines over soft foundation soils. In this technique the reinforcement is placed at the base of the embankment above the pile caps to ensure that negligible embankment loading is transferred directly to the soft foundation soil between the pile caps. In order to transfer the embankment loading directly to the pile caps the reinforcement has to deform. For large embankment heights the deformation of the reinforcement and its adjacent embankment fill is contained within the height of the embankment and thus, does not affect the embankment surface. For low-height piled embankments however, the deformation of the reinforcement and its adjacent fill may affect the surface profile of the embankment leading to a loss in serviceability. Serviceability criteria are presented in the paper based on the need to meet specific embankment surface requirements. The effect this has on the design of low-height reinforced piled embankments has been modelled using continuum methods. A set of design curves is presented that enable specific combinations of piled embankment geometry and reinforcement stiffness to be selected to fulfil these serviceability requirements. It is to be noted that serviceability is mainly influenced by piled embankment geometry with reinforcement stiffness playing a secondary role.
The piled embankment technique has been used in Europe and Asia for many years to prevent differential settlements between embankment abutments and piled structures in areas of soft foundation soils. The reinforcement was placed across the top of the pile caps to enable the weight of the unarched embankment fill to be transferred directly onto the pile caps and to counteract the horizontal outward thrust of the embankment fill on the soft foundation.