Analysis of behaviour of embankments on soft clay

Abstract

Over the years, papers have been published to examine the behaviour of soft marine clay foundation subjected to loadings from embankments and widening of embankments. Methods explored have aimed to predict the soil movement and tension cracks along the embankment. In this paper, the finite element program PLAXIS 8.6 has been used to analyze the numerical models of embankments on soft clay. Two cases were considered; a consolidation analysis was carried out to compare results to the field measurements collected from a trial embankment constructed to failure in Muar, Malaysia.

The second case focused on a study of widening of embankment on non-uniform soft clay. Methods studied here include installation of deep mixed columns, sheetpile, diaphragm walls and geotextile. In this study, the over-excavation and soil replacement are combined with the use of sheetpile and diaphragm walls.

The deep mixed column, sheetpile and diaphragm walls ground treatment can significantly reduce total and differential settlements and restrict the lateral movement of the embankment but differential settlements near the edge could not be effectively avoided. Geotextile proves to have substantial effect in preventing settlement of the crest, transverse gradient change and also lateral displacement. As long as walls are designed with an appropriate stiffness satisfying force or moment equilibrium, increasing wall stiffness or interchanging between sheetpile and diaphragm wall is not needed as reduction of soil displacements is not related to the material type and properties.