Field Monitoring of Geogrid-Reinforced and Pile-Supported Embankment at Bridge Approach

Owing to the growing traffic demands, many embankments have to be constructed on very soft soil. To improve the undesirable geotechnical properties of the soft soil, the geogrid-reinforced and pile-supported (GRPS) embankments are gradually gaining a great reputation as a reliable and cost-effective treatment for time-limited construction projects or complicated geological conditions. This paper describes an in-situ monitoring of the GRPS embankments with three different pile spacings at the bridge approach over the soft soil foundation. The earth pressures and the settlements both on top of the pile caps and the soil surface around the piles, the pore water pressures, and the lateral displacements of the foundation soil were recorded during and after the filling stage. Based on the important measurement data within 280 days, the behaviors of the GRPS system were monitored and discussed in detail. The monitoring data revealed that the measured earth pressures acting on top of the pile caps were 9.56-16.03 times greater than those acting on the soil surface around the piles, reducing simultaneously the excess pore water pressures in the foundation soil. The measured settlements and the lateral displacements of the soil were relatively stable and gradually converged after about 140 days. The stability of the embankments was significantly strengthened by the GRPS technology. Moreover, the change of the pile spacings made the pavement smoother. As a result, an acceptable treatment effect was achieved for vehicle bump at the bridge approach.