For the embankment constructed on soft clayey subsoil

the soft clay generally has large void ratio

high water content

high compressibility

low hydraulic conductivity

low shear strength. Not only large vertical and lateral displacement of soft subsoil will happen during the embankment construction but also sliding failure maybe occurs due to the insufficient bearing resistance of soft subsoil. For this reason

embankment is constructed stage by stage to make subsoil consolidation under embankment loading and to make the soft subsoil acquiring strength from consolidation. This paper presents a case history of a stage constructed embankment on soft high sensitive Ariake clay. In order to speed up the consolidation

prefabricated vertical drain was installed in soft subsoil to increase the vertical hydraulic conductivity of soft subsoil in the macro sense. Field measured results show that during consolidation

water content of soft subsoil decreased and its unit weight increased. The undrained shear strength increased to twice of the original value.