Foundation behaviour below an embankment on soft soils

The Sunshine Motorway is one of the major traffic corridors that service the South East region of Queensland, Australia. Initial investigations for the construction of pavements in area 2, stage 2 of the motorway began in late 1990. Large areas of soft, highly compressible organic clays were found to exist over the length of the upgrade. Also, because the topography of the proposed alignment was mostly low lying, earthworks were required over a large portion of the route. Prior to any earthworks for the stage being undertaken, a trial embankment was constructed in the area to provide an understanding of the foundation behaviour and to also ensure the overall success of the project. The finite difference code FLAC was employed to investigate the performance of the full-scale trial embankment, and the underlying soft clay. Predictions of the excess pore pressure and both vertical and lateral displacements are made and compared with field observations.