Use of Geofoam for Road Construction over Very Soft Clay

Abstract

AbstractDue to scarcity of good land, many highways are bound to be constructed on marshy lands consisting of soft to very soft clayey soil. Some ground improvement techniques like sand drain/PVD with preloads are normally being adopted in most of the cases which is usually time-consuming process. Use of geofoam minimizes the construction time. Geofoam is expanded polystyrene (EPS) manufactured into large lightweight blocks having density nearly 1% of the density of traditionally used filling soil. The primary function of the geofoam is to provide a lightweight fill in the embankment. Due to a lightweight fill material, the dead load of embankment decreases which results into lesser consolidation settlements. Thus, the chances of shear failure of soft foundation soil reduce. A laboratory study on scaled model has been conducted to obtain the differences in stresses coming onto the soft foundation soil due to use of geofoam as filling material in place of traditional filling soil used for roadway embankment construction. In this paper, a comparative study between embankments with and without geofoam has also been carried out. It is observed that the stress on foundation soil is much less in case of embankment with geofoam. A numerical model has been made using PLAXIS 3D for parametric studies. Reduction factors (RFs) for stress were introduced. For given undrained shear strength and given thickness of geofoam layer, design charts of reduction factors were prepared. Finally, it is concluded that geofoam can be suitably used in Indian construction industry.KeywordsGeofoamRoad embankmentSoft clay