Investigation into Some of the Engineering Properties of Soil: A Case Study in Seka town, Jimma Zone

Abstract

Proper understanding of Engineering properties of soils is almost important in any location where all structures are to be founded. Many damages to structures founded on soils are mainly due to the lack of proper investigation of substructure condition. The main aim of this study is to investigate some of the engineering properties of soils found in Seka town in order to know 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. Laboratory tests were carried out including specific gravity, natural moisture content, Atterberg limits, unconfined compressive strength, consolidation, compaction and permeability tests. Based on the results of this study, the grain size distribution indicates all soil samples have more than 90% fine grained material. Therefore, clayey silty type of soil is dominantly located in the study area. The specific gravity of the soil ranges from 2.65 to 2.77. While the Atterberg limit tests results, the soil is highly plastic clay and highly plastic Silt. The values of Liquidity Index classify the soil under the class of Intermediate strength, which the soil deform like a plastic material. The compaction test result shows that maximum dry density (MDD) ranges from 1.180 g/cm3 to 1.480 g/cm3, and the optimum moisture content ranges 35.9% to 48.00% include both methods of compaction. In addition, the unconfined compressive strength of the Seka soils ranges from 143.52kN/m2 -352.92kN/m2 and undrained shear strength range from 71.76 kN/m2 –176.46 kN/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 0.23 and 0.39, swelling index 0.19 and 0.02. The coefficient of permeability (3.75*10-5 to 2.75*10-4 cm/sec) indicating that the soil investigated is impermeable.