A Review On Performance Of Stone Columns As A Ground Improvement Technique: Lessons Learnt From Past Experiences And Prospect For Future Development

Since the population growth is creating a strong demand for urban development, the need for construction in soft soils is dramatically increasing. Accordingly, ground improvement is an important requirement to avoid problems such as non- uniform settlements, failure due to low bearing capacity or liquefaction. Stone columns are used as one of the ground improvement techniques to stabilize the soil through increasing soil stiffness and shear resistance while decreasing the compressibility and settlement. Predicting the behaviour of a stone column needs to meet technical challenges, particularly in soft cohesive soils. Therefore, the aim of this paper is to make a broad assessment of the performance characteristics of stone columns in clayey soils as a review. In this study, the stone columns behaviour has been studied through analytical, experimental and numerical techniques, and failure modes and design of stone columns and their installation techniques are discussed. Based on previous investigations, it is gathered that in very soft soils, the dry-bottom feed vibro replacement technique is preferred to other methods and usage of geosynthetic encasement is very efficient where insufficient lateral confinement of the soil is problematic. According to past findings, the friction angle of the stone material and the diameter of the column are significant parameters for the design of the bearing capacity of the column. Furthermore, apart from ground improvement benefits, stone columns are used as vertical drains, which can decrease the pore water pressure during earthquakes and therefore mitigate the liquefaction potential. In addition, the cost-effectiveness of using low priced materials instead of aggregates without disturbing the overall performance of stone columns seems to be viable and can be explored further in future. This review can give an enhanced viewpoint to engineers and practitioners considering the use of stone columns in their projects.