Abstract: In all Civil Engineering Structures, preparation of foundations for construction of structures assumes a lot of significance from the point of view of strength and stability. Due attention is required to be paid to this aspect. Ground Improvement techniques and Ground replacement are adopted for improving the strength characteristics. It is quite possible that a combination of these methods may also be used. Also rapid urban and industrial growth demands more land for further development. In order to meet this demand, land reclamation and utilization of unsuitable and environmentally affected lands by adopting one or more ground improvement techniques. The Boussinesq method uses elastic theory to calculate stress distribution in an elastic half space due to a point load. By integrating point loads over a specified area, the stress distribution in an elastic half space can be obtained under foundations and footings of different shapes. The main disadvantage of the Boussinesq method is that it assumes a homogeneous material. But, in general, the soil is stratified. For soil layers with high stiffness contrast, the Boussinesq solution can produce large errors in stress. The Westergaard equation (1938) are thought to provide better results for layered media, however the solution essentially smear out the effect of the different layers so that large errors will still occur for a finite number of layers with high stiffness contrast. The cardinal aim of the present work is to understand the effect of replacement of soil by more competent granular fill consisting of combination of 6mm metal and sand in different proportions. Accordingly, the investigation considers the granular material in different combinations of sand. The granular material is used in conjunction with four different types of soils in order to bring out relative effects on stress distribution. Keywords: Elastic moduli, granular fill, ground improvement, layered soil, soil-structure interaction, stiffness
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