Hertsby case: A column stabilised and geotextile reinforced road embankment on soft subsoil

A geotextile reinforced road embankment on deep stabilisation columns in soft subsoil has been studied. At the test case, there has been built a new bridge over Sipoo River. The deep stabilisation has been used to improve the very low stability (F less than or equal to 1) of the bridge embankments. The thickness of the very soft silt and clay layers beside the Sipoo River are 10...20 m. During the stabilisation the displacements of the riverbanks were monitored with inclinometers and the pore pressure was measured with piezometers. Over the stabilised columns there is a woven georeinforcement, which is used to improve the arching in the embankment material and to carry the load between the columns on-to the columns. The instrumentation and measuring results of the geotextile and the embankment have been presented and the measuring results have been verified with FEM-calculations.