Embankment supported on piles with biaxial geogrids

Abstract

The case study consists of a piled embankment built over a very soft, organic compressible clay layer 10 m deep. The height of the embankment supported on piles was about 1·3 m, and the piles, which measured 0·18 m × 0·18 m, were spaced 2·5 m apart in a square pattern, with 0·8 m wide square pile caps covered with a bidirectional 200 kN/m geogrid polyester reinforcement. A region of the piled supported embankment was instrumented to provide a better understanding of the overall embankment-reinforcement-pile cap system. Three-dimensional and two-dimensional pile layouts were adopted. An excavation of 1 m under the geogrid was carried out to induce rapid load transference to the geogrid. The settlement in between pile caps was 0·10–0·4 m, whereas settlements in the region under similar embankment heights were much higher, thus demonstrating the efficacy of pile-supported embankments with geogrids in controlling settlements. Strains at the reinforcement were also measured, and showed values in the range 0·25–2·05%.