STRENGTH AND SETTLEMENT STUDIES OF BLACK COTTON SOIL REINFORCED WITH GRANULAR PILE

Ground improvement, is the modification of existing site foundation soils to provide better performance under design and/or operational loading conditions. Ground improvement techniques are used increasingly for new projects to allow utilization of sites with poor subsurface conditions. The most commonly used techniques suitable for cohesive soils and cohesionless soils have been briefly discussed in this paper. Recent advances made at MANIT, Bhopal to tackle with the problems of construction in black cotton soil have been discussed elaborately. Use of granular pile in such soils has shown that the soil strength on wetting could be improved significantly. The granular pile is found to improve the load carrying capacity of a footing to varying degree depending on the initial consistency of the soil, inclusion of fibres and encasement of the pile material by geogrid. Further, it is found that the swelling of the soil decreases by the use of granular pile in soft black cotton soil. The reduction in swelling depends on the size of the granular pile and initial moisture content in the soil; a larger diameter pile and at low initial moisture content, greater reduction in swelling is observed. Field application of both the techniques is yet to be studied. However, a case study to illustrate use of each of the above new techniques on poor soils, other than the black cotton soil, has been brought on board as illustrations.