Investigation on some of the engineering properties of soils found in sokoru town

Abstract

Proper understanding of Engineering properties of soils is utmost important in any location where all structures are to be founded. The study area of this research is located at Sokoru town, North east of Jimma as part of Jimma Zone. The objective of this study is to investigate some of the engineering properties of soils found in Sokoru town in order to understand clearly the nature of the soil and also to give information for the design, construction and environmental assessment, so that suitable foundation can be recommended for better design and construction in the town. From reconnaissance survey, it has been observed that the Town is covered by red clay soil. Representative disturbed and undisturbed samples from ten test pits were collected from different parts of the town.Laboratory tests were carried out including specific gravity, natural moisture content, Atterberg limits, unconfined compressive strength, consolidation, free swell, Gradation analysis and permeability tests. Based on the results of this study, the grain size distribution indicates all soil samples have more than 50% clay material. Therefore,clay type of soil is dominantly located in the study area. The specific gravity of the soil ranges from 2.5 to 2.73. While the Atterberg limit tests results, the soil is highly plastic clay, and the degrees of activity of most of the study area soils are inactive with maximum Activity index of 1.19. The soil has free swell between 8 % and 49% which also indicaes the soil is not expansive soi. The consistency of soils which are stiff to hard as identified based on the liquidity index value. The compaction test result shows that maximum dry density (MDD) ranges from 1.22 g/cm3 to 1.39 g/cm3 and the optimum moisture content (OMC) ranges from 27% to 37%. In addition, the unconfined compressive strength of the soils in the study area ranges from 154.12kN/m2 -354.21kN/m2 and undrained shear strength range from 77.1kN/m2 –177.12kN/m2 . Likewise, consistencies of the soils ranges from stiff to very stiff. One-dimensional consolidation tests were done, of which the result showed that the soils have compression index rangs from 0.23-0.39, swelling index ranges from 0.19-0.02. The coefficient of permeability (4.58*10-4 to 3.11*10-5 cm/sec) indicating that the soil investigated is impermeable