EFFECT OF ENCASEMENT LENGTH ON GEOSYNTHETIC REINFORCED STONE COLUMNS

Being cost effective and environmental friendly, stone columns are used worldwide for supporting flexible structures such as embankments, oil storage tanks etc. which can tolerate some settlements. However, when the stone columns in very soft soils are loaded; stone columns undergo excessive settlement due to low lateral confinement provided by the soft soil, leading to the failure of the structure. The excessive settlements may be avoided or at least reduced to a great extent, when the columns are reinforced with geosynthetic. The technique of wrapping the individual stone column with a suitable geosynthetic (encasement) is one of the reinforcement modes which improve the performance of stone columns. In this study, model tests were performed on single floating as well as end-bearing stone columns with and without encasement. The column was reinforced by providing geosynthetic encasement over varying column length. The tests indicate that the encasement over the full column length gives higher failure stress as compared to the encasement over partial length of column for both floating and end bearing columns. Further, the performance of end-bearing columns was found to be better than the floating columns