Class A and Class C numerical predictions of the deformation of an embankment on soft ground

Abstract

The performance of a trial embankment on soft ground treated with wick drains has been predicted, in terms of total surface settlement, lateral movement, and dissipation of excess pore pressure. The settlement performance was predicted on the basis of hand calculations, carried out in a spreadsheet, using the classical radial consolidation equations of Barron and Hansbo. This was followed up with numerical analysis using 2-D finite element code in PLAXIS 2D2016, employing their soft soil creep model. Analyses were carried out on a single cell, for comparison with the hand calculations, using both axisymmetric and plane strain models. An analysis was also carried out in plane strain for a section through the whole embankment. This was used to predict the lateral movements and also the dissipation of excess pore pressures at selected points, for comparison with measured data from instruments.After the results of monitoring the trial embankment were published, the numerical model has been modified and shows excellent agreement with the measured data. A description of the modelling is provided, as well as details showing the limited way in which the model has been modified.