Geotechnical Characterization and Foundation Analysis for Selected Sites under Addis Ababa Housing Projects, Addis Ababa, Ethiopia Merga Negasa A Thesis Submitted to School of
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Date
2014-05
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Addis Ababa Universty
Abstract
Mass housing projects always paid less attention due to their bulkiness and sometimes failures of buildings occur before their performance stage. It is obvious in such cases the proper ground investigation and characterization will not practically fulfilled, where less and poor routine subsurface investigation is conducted. The city government of Addis Ababa had been practicing construction of massive housing projects and also launched new low cost housing projects to meet urban renewal strategic plan. These projects are vast and construction is booming throughout the city. One of the most recent failures of building in Addis Ababa was occurred at Jemo condominium site where massive housing construction was performed. This study characterizes subsurface where such urgent construction would be under way to be employed. Three sites were selected to analyze their suitability for the anticipated building types. Soil index tests were used to characterize the subsurface geological formations and data from excavations and borehole logs were used. Index tests were conducted on the samples collected from these sites. Evaluation of bearing capacity and settlement analysis was conducted. Based on the laboratory results and index soil tests Megenagna and Imperial sites are characterized by fine grained, high plasticity SILT and CLAY soils. Asco site is characterized by fill where the most of the top soil layers of the site are highly compressible, coarse grained material. Excessive settlement was resulted in according to Bowels, (1996) estimation and the sites need extensive ground improvement mechanisms before construction begin. The bearing pressure estimated using Meyerhof, (1963) and Hansen, (1970) shows extreme values which is exaggerated. The buildings have double basements and the foundation depth will be around 7m below the natural ground level. The depth factor is responsible for such results of bearing pressure. Thus, Meyerhof and Hansen bearing capacity equations are not valuable for this study. Key words
Mass house Settlement Bearing capacity Foundation Clay Silt
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Keywords
Mass house, Settlement, Bearing capacity, Foundation, Clay, Silt