Examing the relationship between index properties and swelling pressure of expansive soil found in welkite town

Abstract

A considerable Welkite town surface area is covered by expansive soils which have a tendency to undergo volume change due to change in water content with seasonal moisture variation. Civil engineering structure built on such soils show damage due to uneven movement caused by swelling and shrinking of the soil. The focus of this study is to develop relationship between index properties and swelling pressure of the expansive soils found in Welkite town. Conducting swelling pressure test is time taking and expensive when compared with a simple index property tests. Therefore, it is helpful and has engineering applications to develop correlation formulas for estimating the swelling potential from simple index properties tests. The new formulas has been developed, by taking one or more of the soil property parameters (Liquid limit, plastic limit, moisture content, dry density and plasticity index) in different combinations. To develop the equations, 16 test results have been used as an input data for SPSS 21 windows software. The equations are then tested for two control samples. The best equation was proposed, and conclusions and recommendations were made. Lastly, future works were suggested. The test results showed that the Specific Gravity ranges from 2.68 to 2.82. The index property test showed that plasticity index ranges from 46 to 65.1%, liquid limit ranges from 87 to 109%, plastic limit ranges from 37 to 48%, and liquidity index range from -0.15 to 0.18. The clay content of the soil is from 65.89 to 74.62%. Free swell tests conducted on the collected samples showed a range from 160 to 221%. The undisturbed sample test results showed that the swelling pressure of the area ranges between 74 and 390 kPa, ϒd ranges between 1.19 and 1.48 and moisture content range from 34 to 48%. The new formulas were developed, by taking one or more of the five parameters (liquid limit, moisture content, plastic limit, dry density and plastic index) in different combinations. The equations are developed by using SPSS 21 for windows software. Among the equations, equation 4 fulfills the entire requirements.