A full-scale experimental geosynthetic-reinforced piled embankment (GRPE) and its numerical back analysis are presented in this article. The site is in Virvée (France) and is part of the new South Europe Atlantic high-speed line project. The GRPE system was proposed as an optimized solution to replace a classical pile-supported embankment (PE). Based on the full-scale tests, 3D finite element models are considered to simulate both GRPE and PE solutions. The results obtained are presented in comparison with in-situ measurements. Settlements, pile stresses and the geosynthetic strains are investigated. Then, a parametric study is conducted for the GRPE system to evaluate the influences of the pile net spacing, geogrids tensile stiffness and number of geosynthetic reinforcement layers. The results show that the use of a double-layer geosynthetic reinforcement enhances the overall performance of the geosynthetic-reinforced piled embankment.