Browsing by Author "Biniam Yihun"

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    Geotechnical Investigation of some Failed Sections along Omo River-Tercha Road Project
    (Addis Ababa University, 2024-04) Biniam Yihun; Tensay Gebremedhin (PhD)
    This thesis investigates the geotechnical failures within the Omo River-Tercha Road Project, specifically focused on unanticipated premature failures emerged shortly after opening the road for traffic. The study initiated by examining relevant project documents and conducting comprehensive on-site surveys to identify and record signs of geotechnical failures along the project road. Among these, five major geotechnical failures were identified as significant for further detailed investigation: saturation of recently placed pavement materials and surface pumping, erosion on the surface of roadway cut slopes, depression and several cracks in newly placed pavement, failure of roadway cut slopes and failure of roadway side fill slopes. After conducting extensive assessments of each failure, which involved a thorough analysis of available project design and construction data, a detailed on-site investigation to detect signs of failure, soil sampling for laboratory testing to examine soil properties and modeling of road cross-sections at locations of slope failure to identify slip surfaces and calculate factors of safety. As a result, the study revealed significant factors contributing to these premature failures, including inadequate subsurface drainage, removal of vegetation covers, problematic subgrade soil, steep geometry of cut and fill slopes, challenges associated with Design-Build contracts and limited engagement of geotechnical engineers. In response to these findings, the thesis has proposed remedial measures to this newly completed road project. These measures include the establishment of longitudinal interceptor drains for subsurface drainage, re-vegetation with the use of soil erosion blankets, installation of vertical moisture barriers to encapsulate problematic soil, flattening of slopes and integration of geo-grids into the construction of fill slopes within confined spaces. Prompt action is recommended to implement these measures, preventing further damage, minimizing maintenance costs and ensuring infrastructure longevity. The findings provide valuable insights for future road projects, emphasizing proactive geotechnical considerations in design, construction and maintenance.