Centrifugal and numerical modeling of embankment widening over soft soils treated by pile-supported geosynthetic-reinforced soil wall

More and more expressways built on soft soil foundations need to widen their embankments because they cannot fulfill the demand for the traffic volume. Geosynthetic-reinforced pile-supported embankment (GPE) is currently the most widely used method in practical projects. This paper proposes the pile-supported geosynthetic-reinforced soil wall (PGSW) technology to widen embankments, enjoying several evident advantages in construction. The existing embankments with and without piles in the foundation soil were widened by the PGSW and GPE technologies using a centrifugal model to compare these two technologies. In addition, the finite-difference numerical models were established to analyze the cut slope ratio of the existing embankment in the PGSW technology. The results indicate that the settlements of the existing embankment and the widened portion, as well as the differential settlement between the existing embankment and the widened portion, are smaller for the PGSW technology than the GPE technology. The widened portion has less influence on the bending moment of the pile near the centerline of the embankment and the toe of the widened portion in the PGSW than GPE technology. When the PGSW technology is adopted, the settlement on the embankment crest and the horizontal displacement of the lower part of the wall decrease with an increase in the cut slope ratio, and a cut slope ratio of 1.0:0.5 (vertical/horizontal) is advised.