Effect of sodium polyacrylate and impermeable layer applications on soil liquefaction potential

Generally, fine sandy or silty soils in loose and saturated state exposed to dynamic effects lose their bearing capacity due to a decrease of interaction between grains and show excessive settlement during liquefaction. Soil liquefaction takes part of important causing problems in terms of both geotechnical and structural damages in Turkey, which is located in the active earthquake zone. Therefore, studies are needed to prevent this problem. Firstly, a liquefaction mechanism, the factors affecting the liquefaction potential and details about calculations were given within this thesis. Then, literature survey categorized under subheadings as theoretical, experimental and field studies. The main theme of thesis consists of three different experimental studies about liquefaction. The first one is a study that includes the formation of liquefaction and the change in liquefaction with respect to relative density on experimental model. Next, the effect of the impermeable top layer of different thickness on the liquefiable Toyoura and silica sand layer was investigated. Finally, the effect of sodium polyacrylate addition, which offers an alternative solution against the liquefaction problem, into the cohesionless soil with liquefaction problem on soil parameters were evaluated. By placing an impermeable top layer on a liquefiable soil, the highest pore water pressure damping values were observed for both sand samples in 1.50 cm layered soil. In the study with Toyoura sand, the pore water pressure was damped at a rate of 11.04%, this ratio reaches 22.50% in the study with silica sand. The use of sodium polyacrylate on liquefiable sandy soil provides benefits in terms of unconfined pressure resistance and shear strength. On the other hand, it does not have a serious effect on permeability values. As a result, the phenomenon of liquefaction has been studied in detail within this thesis and a unique approach to the solution of liquefaction is presented