Estimating Geotechnical Parameters in Highly Heterogeneous Material Including Peat Deposits using Trial Embankment Data

When designing high embankments over compressible material it is important to have a sound understanding of the characteristics of the materials in question. When dealing with soils that are highly heterogeneous and consist of many layers of different compressibility it becomes difficult to reliably estimate soil parameters from conventional sampling and laboratory testing. In particular, assessing the magnitudes of primary, secondary and immediate settlement can be difficult as the various layers within the soil consolidate at different rates. This can be further complicated by the presence of peat materials which tend to undergo significant amounts of settlement. An instrumented trial embankment was built over a significant thickness of soft material comprising amorphous peats, organic silts, silts and clays. Soil parameters were back-calculated from monitoring of the trial embankment and these were subsequently used to model the embankment’s behaviour using the software package Settle3d. The results of the modelling were then calibrated to create a set of parameters which match the settlement data from the trial embankment.