Investigation in to some of the Engineering Properties of Soils Found in Debre Birhan Town, Ethiopia
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2015-10
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Addis Ababa University
Abstract
This research deals with the investigation in to some of the engineering and index properties of soils found in Debre Birhan town. Disturbed and undisturbed soil samples were collected from Debre Birhan town from eleven test pits in order to conduct and determine the necessary engineering and index properties. Insitue soil properties shows that the natural moisture content for the area under study ranges from 20.11% to 58.99 % and the insitue unit weight is in the range of 14.02 kPa to 18.53 kPa. Specific gravity is between 2.62 and 2.81. The specific gravity is above 2.62 indicating that inorganic soils are dominant as most of organic soils contain a value of less than 2.40. The grain size analysis of the area under study shows the soil contains gravel 0-24.63%, Sand 2.37%-38.74%, Silt 27.28%-55.9% and clay in between 8.77% to 67.5%. This shows that the dominant soil types in the area are Silt and Clay. The liquid limit of the soils is in the range of 31%-80%. Plastic limit of the soils lies in between 18% to 43%. Plasticity index for the area under study lies between 13%-46%. Soil classification for the area under study is made by both USCS and AASHTO. Soils classification by USCS shows that the soil contains around 41% CH, 18% CL, 18% MH, 14% ML, 4.5% SM and 4.5% SC and AASTHO classification system shows the soils are classified in either of A-6 or A-7. The unconfined compressive strength test of soils gave a value of qu between 75kPa to 233 kPa and the amount of cohesion lies in between 37.5 kPa to 116.5 kPa. Consistency is also determined based on the UCS result showing that the soil is medium, stiff or very stiff. Consolidation test was conducted on three different types of soils which are taken based on the classification result. The range of compression index is in between 0.20-0.38 and the preconsolidation
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Civil Engineering