

Within the framework of the regional express network around Brussels, an existing railway line will be extended from 2 to 4 tracks. The extension needs to be realized as much as possible within the existing properties and possess a green character. The chosen solution consists of a stepped embankment at a 45° angle, departing close to the existing embankment toe and with a flat terrace every 1.8 m. For the design of these green terraces, the concept of reinforced earth was adopted. A classic small cantilever wall will be adapted by anchoring a geogrid in the base slab. The cantilever wall acts as a facing element for the reinforced earth fill. In places where the geogrid cannot be sufficiently anchored, the geogrids will be attached to soil nails. Due to the specific geometry, the required high stiffness and the high pH resulting from the concrete curing, a geogrid based on PVA with a high strength of 800kN/m will be used. This system of reinforced earth leads to a lower concentration of loads on the foundation, so a foundation made up from stone columns will be sufficient. The complete system and the interaction between the different structural elements were extensively studied through numerical analysis in FLAC. The embankments are currently under construction. Preliminary testing on the stone columns, soil nails and geogrid anchorage has been carried out.