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Analysis of the performance of encased granular columns based on laboratory and field test data

The coastal deposits all around the world are often marine clays which are in soft to very soft consistencies. They are one such variety of problematic soils characterized by low bearing capacity and high compressibility that necessarily require treatment to enhance their strength and stiffness proper-ties. A wide variety of ground improvement techniques are practiced currently in enhancing the engineer-ing behaviour of problematic soils which include surcharge pre-loading, PVD, granular columns, lime stabilization and recently Vacuum methods etc. Out of these methods, the granular columns have provid-ed promising solutions in soft clay deposits. More recently with the advancements in polymer industry synthetic planar and 3D products have emerged in the field of geotechnical engineering which is indeed an added advantage nowadays in combination with the conventional methods. Geosynthetic encased granular columns are one such recent advancements that can effectively tackle soft soil problems. Very small numbers of field based trials related to geosynthetic encased granular columns are reported in the literature which indirectly indicates the lack of understanding the mechanism of the same. This paper will discuss concisely on the parameters which influence the effectiveness of geosynthetic encased granular columns in soft grounds by reviewing the data collected from published literature. Discussions on the key parameters like the shear strength of soft soil, diameter, length of the granular column, length of the geosynthetic encasement etc., will be included. The analysis will include comparison of the data with the procedures given in German design code (EBGEO) for encased granular columns.