Case History of an Unusual Embankment Failure

The partial failure of a 7.5m high surcharged embankment constructed over soft clay and peat is described. Extensive instrumentation within the embankment and its foundation gave only partial warning of the impending failure. Failure occurred during the final lift of surcharge and resulted in a 0.6m wide tension crack approximately 100m long down the centre line of the embankment. Unusual features included the fill material, lack of pore pressure dissipation during construction despite installation of wick drains, limited lateral deflection prior t o failure, near perfect symmetry of the failure and the remedial measures implemented.