Investigation of an embankment failure in soft clay

Reported here are the results of an investigation into the failure of a low road embankment founded in soft Bangkok clay and flanked by retaining walls. A rotational slip appears to have occurred, the factor of safety of the embankment under its own weight being only about 1.2. While traffic loading was certainly a contributory factor, failure was probably caused by the excess pore pressures generated in the soft clay when long concrete piles were driven adjacent to the retaining wall as a remedial measure.