Tadesse, Samuel(PhD)Enawgaw, Abraham2018-06-122023-11-112018-06-122023-11-112005-01http://etd.aau.edu.et/handle/12345678/528It has been very common to see collapse of structures, slopes, and foundations due to flow of foundation soils without observing any structural failure during earthquake. This can also occur frequently and cause severe damages in this country following the occurrence of earthquake, particularly in the Rift Valley region where there is a considerable deposit of saturated sand and silty sand. This problem has been studied in various countries and attributed to Liquefaction Phenomenon. The phenomenon occurs in saturated sand, which either completely loses its strength and flow as a liquid (Flow Liquefaction, F.L) or shows a progressive softening (Cyclic Mobility, C.M.) under cyclic loading. Since liquefaction of sand is entirely related to its undrained behavior, the undrained behavior of saturated sand under cyclic or equivalent monotonic loading has been studied in the laboratory by different researchers, simulating field conditions properly for the better understanding of liquefaction phenomenon. The undrained behavior of saturated sand is useful to predict the occurrence of the probable type of liquefaction (C.M. or F.L) and to provide suitable solutions for liquefaction problem. The objective of this research is therefore to study the undrained behavior of saturated sand in relation to liquefaction phenomenon based on intensive literature survey. This is best explained by identifying factors affecting the behavior and studying their effects observing the resulting stress-strain and p-q diagrams. The concept of Liquefaction and steady state are then discussed based on the undrained behavior of sand. Finally, the application of Steady State Line (SSL) on the assessment of liquefaction potential and in the identification of partial liquefaction, limited liquefaction, and complete liquefaction is discussed.enPartial Liquefaction; Limited Liquefaction; and Complete LiquefactionThesis