Investigation in to Some of the Engineering Properties of Soils in Dembecha Town, Ethiopia
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Date
2015-09
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Addis Ababa University
Abstract
It is vital to carry out geotechnical investigation of soils before the design of any civil engineering works as soil is the ultimate foundation material. In addition, the recent growth which is associated with urbanization in Dembecha Township calls for appropriate geotechnical investigation of soils of the area.
This work focuses mainly on the investigation into some of the engineering or geotechnical properties and prepare soil map of the study areas in Dembecha town. The area under study encompasses places of infrastructures and future expansion as per the information from the mayor’s office.
Representative disturbed and undisturbed soil samples were collected from ten open test pits and were investigated for their geotechnical properties with a view to classifying for their suitability, applications or otherwise for infrastructural development.
The study area is mainly covered by two types of soils. The first groups of soils are red soils which are classified as inorganic clay and silts according to Unified Soil Classification System. These soils have a specific gravity ranging from 2.80 to 2.84, liquid limit of 61% - 80%, plasticity index of 28-41%, percent dispersion of 0% - 3.34%, clay fraction of 71.52% - 79.83%, compression index of 0.176, recompression index of 0.015, pre consolidation pressure of 200 kPa, coefficient of permeability ranging from 0.168*10-9 to 1.375*10-9 cm/sec and free swell values of 30% - 50%.
The second groups of soils are brown soils which are all classified as inorganic clay except one test pit which is classified as inorganic silt according to Unified Soil Classification System.These soils have a specific gravity ranging from 2.73 to 2.85, liquid limit of 59% - 89%, plasticity index of 26% -59%, percent dispersion of 8.32% - 78.40%, clay fraction of 45.15% - 65.69%, compression index of 0.191-0.197, recompression index of 0.026- 0.059, pre consolidation pressure ranging from 100 to150 kPa, coefficient of permeability ranging from 0.083*10-9 to 1.237*10-9 cm/sec and free swell values of 40% - 93%.
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Civil Engineering