PERFORMANCE OF STONE COLUMNS TREATED DRY SAND BED UNDER CYCLIC LOADING

Abstract

Use of stone column is a widely accepted ground improvement technique and is used very frequently now a days. Stone columns are used for strengthening of weaker soil strata to support hiegher intensity of loads and for a longer duration of time. Stone columns are generally made up of crushed stones but now a days some additives are also used to improve the efficiency of stone columns. Stone columns may also be reinforced by geosynthetic materials, which greatly effect the properties of stone columns. Soil bed resting over the top of stone columns also effects the strength of stone columns, that’s why sometimes this soil strata is also strengthened by geosynthetics. Stone columns are used for reinforcement of all types of soils like sand, silt and clays. A lot of work has been done to understand and improve the capacity and efficiency of stone columns by different researchers and scholars. Still some gaps are left in literature which need to be filled by further study. In current work an attempt has been made to add some additional value to the literature related to stone columns. In current experimental study effect of a number of parameters on vertical settlement of different footings (square and rectangular) have been examined. The results of this study show that these parameters have more or less same effect on footings as expected from the review of existing literature. In case of rectangular footings more settlement has been observed when loading was applied in the direction perpendicular to the length of the footing as compared to the case when loading was applied parallel to its length. Optimum length of stone columns has been found to be approximately 13 to 16 times the diameter of stone columns and optimum spacing between stone columns should approximately be 2-3 times their diameter.