Geosynthetic reinforcement of pile-supported embankments

Rigid piles are used to reinforce soft soil foundations and thus increase embankment stability. This technique is improved by placing one or more geosynthetic reinforcement (GR) layers inside or at the base of the embankment. A series of 33 small scale models were tested using a geotechnical centrifuge. Soft soil settlement was imposed by the downward displacement of a tray. First, a series of models were prepared to examine how the load transmitted to the pile network increased with the embankment thickness. Using the same configuration, two identical models were prepared to successively test two different types of GR (geosynthetic reinforcement). Another approach was used to study how the external surcharges applied on the embankment affect load transfer. The results showed that, compared to the piled embankment, the load transfer increased for the case of the geosynthetic-reinforced pile-supported embankment (GRPSE) due to the membrane effect. The membrane effect is higher when the GR is stiff and its vertical distance from the pile is reduced. Numerical modelling reveals that, when another GR layer is added, the second GR has an effect only if punching is sufficient. However, the second layer did not reduce embankment settlement.