Behaviour of 60-year-old trial embankments on peat

Abstract

The search for low cost solutions for roads on peatlands inspired the construction of four full scale trial embankments at two sites in Norway in the early 1960's. The embankments are still accessible and this work was motivated by present day needs to develop environmentally sustainable solutions to such problems. The embankments were constructed using locally sourced sand and sawdust and have behaved very well with the sawdust settling beneath the water table as designed and remaining in perfect condition some 60 years later. A detailed characterisation of the distinctly different peat at the two sites is presented and it is shown that the peat properties are as expected from local and international experience. Laboratory work on the sawdust showed that it behaves like a highly compressible fibrous peat. Short-term embankment settlement behaviour was controlled by the level of applied load whereas long-term creep settlements were governed by the peat consolidation properties. Pore water pressures dissipated unexpectedly quickly. Modelling using the Soft Soil Creep model in PLAXIS captured both short- and long-term settlements and the pore pressure dissipation well.