Correlation Between Index Properties And Swelling Characteristic of Expansive Soil
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Date
2014-07
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Addis Ababa University
Abstract
In some parts of Ethiopia large surface deposits are covered by expansive soils. Such soils have the characteristics of swelling and shrinkage up on change in water content with seasonal variation. These swelling and shrinkage are generally confined to the upper portions of the soil deposit and cause considerable damage to lighter structure such as small buildings and highway pavements if not adequately taken care of. This damage is due to development of swelling pressure when expansive soils come in contact with water. Therefore, main purpose of this research is to determine the swelling pressure of these soils and also to develop an equation for quick prediction of swelling pressure from easily determined soil properties for this research area.
In order to examine the relationship between index properties and swelling characteristic of the soil, both undisturbed and disturbed soil samples were obtained from seventeen different test pits in different locations at depth of 1.5 – 2.0m. Then laboratory tests including swelling pressure tests, mineralogical identification tests and index property tests were conducted. After having all the test results, new correlations of swelling pressure have been carried out by stastical analysis using linear regression analysis method (SPSS 20 Computer program) for prediction of swelling pressure using liquid limit, plasticity index, shrinkage limit, initial moisture content, free swell index, liquidity index and initial dry density of the soil.
Soils of the studied area are identified as moderately to high swelling expansive soils containing high plastic clay and high compressible silt particle. The analyses carried out have confirmed the existence of strong correlations between the swell pressure and its index properties. The correlations revealed a simple regression equation for a quick prediction of swell pressures from easily determined soil properties.
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Geotechnical Engineering