Failure of a trial embankment on peat in Booneschans, the Netherlands

A trial embankment 6 m high was built on peat in the Netherlands, and brought to failure. The aim was to test whether innovative sensor technology could detect incipient failure in time. However, the data generated also made it possible to conduct a geotechnical assessment of stability. The paper discusses the relation between the parameters derived from laboratory tests, field measurements and behaviour observed in the field. Problems encountered in the standard triaxial testing of peat samples are discussed, as the samples tend to fail in tension. A trial pit through the failed embankment showed that there were wide tension cracks in the peat layer, indicating that the peat layer failed in tension, at least locally. However, horizontal movement dominates the overall failure mechanism. As an alternative to triaxial testing, direct simple shear (DSS) testing for the assessment of peat parameters is considered. The results of the DSS tests correspond well with field measurements and the back-analysis of the failure.