Fildrain 7DD and Fildrain 7DHD geocomposite drainage layers are the most advanced system for relieving pore pressure in the construction of new rail embankments. This proven method of construction has BBA certification for the starter layer and subsequent layers through the height of the embankment to aid consolidation without expensive aggregate.

Full settlement of new rail embankments must be achieved before the surface is constructed and embankment fill is placed at the optimum moisture content for compaction. This invariably means that the compacted fill, as a result of pore pressure, is too wet to support long term loads without settlement. Relief of pore pressure and speed of consolidation is therefore critical to deliver projects on time and within budget.

Fildrain geocomposites are used to create horizontal drainage layers at typically one metre vertical spacing for quick reduction of pore pressure. Compared to crushed stone, it is cost effective to install Fildrain at close spacings. Fildrain is also impermeable in the vertical plane which means that each layer protects the earthworks from the ingress of rainfall.

Projects have been fully consolidated in 25% of the time normally expected compared to traditional methods. Fildrain geocomposite even enables the use of wet material that would otherwise be unsuitable for embankment construction. This allows greater use of site-won fill which minimises earthworks movements.