Engineering Geological Characterization of Expansive Soils in Nifassilklafto Sub-City Jemo Area, Addis Ababa, Ethiopia
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Date
2021-03-02
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Addis Ababa University
Abstract
The present study was carried out in Addis Ababa NifasSilikLafto sub city Jemo area with the main objective of characterizing the expansive soils found in Jemo area.
Expansive soil in many parts of Addis Ababa poses significant damage light buildings. Therefore, identification, evaluation and characterization of them is a paramount importance to address the problems.
In the present study characterization of such expansive soil was adopted by identification and classification based on their laboratory results, correlation of swelling potential and compression indeces with index tests and correlating the laboratory derived and new calculated compression indices values with the well-known skemptons relationship.
In order to prepare a geotechnical data base a large quantity of drilling and laboratory testing data, have been filtered out and systematically organized to derive a new relevant correlation for the selected soil type in Microsoft excel. The output of the collected soil sample data is further checked by using five test pits and subsequent soil sampling and laboratory analysis of the most common index laboratory tests according to ASTM standard.
From the present study based on the available systematically organized drilling geotechnical data the thickness of expansive soil ranges from 3m to 16m in the study area. The depth profile generally tells that Dark grey silty CLAY/ clayey SILT as a top soil, Light grey silty CLAY/ clayey SILT, Clayey silty SAND having variable thickness. The soils are categorized as CH-clay with high plasticity (fat clay) and MH- CLAY according to the Unified Soil Classification System.
Finally based on the correlation between index and swelling pressure no well-defined relationship was found to occur between swelling pressure and index properties. Results of correlations and analysis of compression indices with Liquid Limit and plastic limit show that Cc values generally increases with increasing liquid limit and plasticity index of soils. This serves to suggest that compressibility of soils generally increases with increased plasticity.
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Characterization, Expansive Soils, Swell Potential, Plasticity, Compression