Samuel Tadesse (PhD)Tigist Gemechu2023-12-142023-12-142023-07http://etd.aau.edu.et/handle/123456789/919Undrained shear strength of clay soil is a very important feature in geotechnical engineering. Obtaining undisturbed samples and testing them is a tough and time- consuming procedure; any experiment aimed at obtaining correlations between shear strength and consistency limits would be extremely beneficial. In this thesis, efforts have been made to obtain valid correlations between undrained shear strength and Water content ratio (WCR) for saturated soil samples and for unsaturated soil samples suction values were obtained from previous proposed mode of SWCC then suction value and undrained shear strength were correlate. For this purpose, Red clay soil samples collected from different sites in Addis Ababa city at the depth of 3m were used. In addition to collected soil samples secondary data were used. And for each samples Atterberg limits, Specific gravity, Sieve and hydrometer analysis, Compaction tests were conducted beside that by remolding these samples Unconfined Compressive Strength (UCS) tests were conducted. The best fit line, correlation, regression analysis, and comparison were performed using EXCEL. The findings are expected to have a wide range of applications in construction, making it easier for designers to produce a solid, cost-effective, and dependable design.en-USWater content ratio, Undrained shear strength, Liquid limit, Water contentThesis