Developing Correlation Between the Index Properties and Swelling Potential of the Expansive Soils Found in Wolisotown
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Date
2016-02
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Addis Ababa University
Abstract
A considerable surface area of Woliso town 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 correlation between index properties and swelling potential of
the expansive soils found in Woliso town. Conducting swelling pressure and swelling potential
tests 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 thesis investigated the feasibility of single linear regression analysis and multiple linear
regression analysis in correlating swelling potential with soil index properties. A total of 19
disturbed and 19 undisturbed samples were collected from different localities of Woliso town and
the necessary laboratory tests were conducted in order to develop the empirical correlations.
In this research regression analysis is used to explore the significance of individual independent
(index) soil variables. The empirical correlation is given in the form of an equation of swelling
potential as a function of natural moisture content, dry density, grain size analysis, Atterberg
Limits .This is done by considering the effect of an individual soil index properties and effect of a
combination of soil index properties on the swelling potential results. The empirical correlation
using single regression analysis results in a determination coefficient of R-square (R 2) =0.3864
and mean confidence level of (CL)=96.78%, whereas multiple regression analysis gave
comparatively a better correlation with determination coefficient of R-square (R 2) =0.4886 with
mean confidence level of (CL) =95.82%. Results of the validity of the newly developed correlation
with control test results shows that, the correlation of swelling potential value with soil index
properties is valid only for preliminary design purposes and estimation of swelling potential of the
soils.
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Geotechnical Engineering