Pile-supported embankment over soft soil for a high-speed line

In the construction of the new South Europe Atlantic high-speed line, many embankments have been built on very soft soil. In particular, to access the new bridge constructed above the Dordogne River, a high embankment has been constructed on peat and clay. To minimise the expected settlement and to reduce construction time, a pile-supported embankment (PE) was initially designed based on driven precast concrete piles with a square pile head. A geogrid reinforced piled embankment (GRPE) system was proposed as a ground improvement method to replace the initial choice. To compare the efficiency of the GRPE system and the PE system, a full-scale experimental reinforced embankment was established. The measurements show that the GRPE system shows less settlement and is more stable than the PE solution, and therefore performs at least as well as the PE solution: the settlement is reduced and stabilised, the load is transferred to the piles and the maximum geogrid strain occurs at the end and around the pile heads in the lower geogrid.