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Title: FURTHER INVESTIGATION OF ROAD FAILURES CONSTRUCTED ON EXPANSIVE SOILS OF CENTRAL ETHIOPIA ADDIS ABABA-JIMMA ROAD AS A CASE STUDY
Authors: AWOKE SIME JIMILU
Advisors: MESSELE HAILE (Dr-Ing)
Copyright: 2006
Date Added: 13-Oct-2008
Publisher: Addis Ababa University
Abstract: ABSTRACT Expansive soil covers an appreciable part of Ethiopia. Currently different construction activities are taking place, especially in road sector, on expansive soil. It has been noticed that constructions on expansive soils face numerous problems and some attempts have been made to investigate the causes of the problems in some parts of the country where these soils are prevalent. Most of the roads constructed in Ethiopia on this type of soils fail before their expected design life in some cases even after few months of completion. In this study failure of roads constructed on expansive soils of central Ethiopia, with special emphasis on Addis Ababa - Jimma road are investigated. Italians, in 1930 G.C, initially constructed the road. Since 1998G.C the road is under rehabilitation. In the year 2000 the Contractor started construction of wearing course and after three months the Consultant’s personnel have found cracks in some portions of the newly constructed road. In the following months the cracks aggravated and additional cracks were also seen. In this study an attempt was made to investigate the causes of failure. The study focused on performing field tests, taking representative pavement material samples from different portions of the road and making the necessary laboratory tests on the collected samples. Additional natural subgrade samples from left and right hand side of the road were also taken for laboratory testing. From the field and laboratory test results it is concluded that the materials used are according to the design specification, on the other hand, the field density results showed a relatively lesser value than the required. In areas where failure has not occurred the CBR values related to the field density are in accordance with the specification, but in areas where failure have occurred the CBR values related to the field density are lower than what is required especially in the base course layers. The natural sub-grade has been found highly expansive and observation has been made that expansive soil was used, when Italians initially constructed the road, as an embankment fill material in areas where expansive natural sub-grade is prevalent. Poor drainage conditions are also observed in sections where failure has occurred. The poor drainage condition together with the disturbance created during the rehabilitation work on the highly expansive soils are the major causes of Addis Ababa – Jimma road failure
Description: A Thesis Submitted to the School of Graduate Studies of Addis Ababa University in Partial Fulfillment of the Requirement for the Degree of Master of Science in Civil Engineering
URI: http://hdl.handle.net/123456789/1394
Appears in:ILS Proceedings - The 19th Annual Conference

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