In situ failure test of high water content soft clay embankments reinforced by GHDs

To apply newly developed geosynthetic horizontal drains (GHDs) to reinforced embankment, full scale in situ failure tests were carried out. The GHDs consist of geosynthetic materials which have improved fabric parameters for permeability and reliable strength. Four kinds of GHDs were selected and a very soft clay with a high water content was used for the filling material. In this paper, the properties of GHDs used were introduced and the design procedure for the reinforced embankment including (drainage by GHDs was discussed. Highly critical values for safety of the embankments were selected. The filling frame was made with sandy soil and the soft clay soil embankments was designed to be 3m high with a 1:0.5 slope angle. Execution steps of the embankment and failure patterns of the test embankments are summarized. The induced excess pore water pressure and deformation of the embankment, etc. were carefully monitored during the embankment works. The results obtained reveal that the assumed critical safety factor of the slope closely coincided with the limiting loading height and the GHDs provide sufficient reinforcement.