The S'Gravendeel High Speed Railway embankment trial is monitoring the performance of five types of embankment, each constructed on 9m of soft clay and peat overlying dense sand.
Reference embankment built with vertical drains and designed by GeoDelft to standard Dutch practice (HW1).
Lime-Cement columns carried out by Dutch contractor NGT in partnership with Stabilator of Sweden and the Swedish Geotechnical Institute, forms part of the EuroSoilStab project (HW2).
Fraise mix injection, a German method which uses a giant chainsaw trencher to form 1m wide lime-cement mixed in place trenches at 2.5m spacing along the long axis of the embankment. This technique was engineered by Geo International and constructed by German companies Leonard Weiss and Sidla & Schonberger in conjunction with Dutch partners KWS and NBM (HW3).
Geotextile covered sand columns. Another German technique, this involves installing 1.5m diameter geotextile covered sand columns, on a close centred grid, into the Pleistocene sand. As load is applied the columns become slightly squatter causing the textile to tighten around the column shaft increasing its stiffness. This method is cost effective, but ensuring a watertight seal at the top of the sand involves tight construction control. Designed by Prof Kempfert & Partners, contractor Mobius (HW4).
Foam concrete piles formed inside PVC casing with a geogrid load transfer platform. Embankment is made of stabilised clay and peat. Engineered by Vermeer Infrastructuur, in conjunction with Huesker for the supply and design of the load transfer platform geogrid (HW5).