This study is focused on developing a method to predict the dynamic behavior of mine tailings dams under earthquake loading. Tailings dams are a by-product of coal mining and processing activities. Mine tailings impoundments are prone to instability and failure under seismic loading as a result of the mechanical behavior of the tailings. Due to the existence of potential seismic sources in close proximity to the coal mining regions in the United States, it is necessary to assess the post-earthquake stability of these tailings dams. To develop the aforementioned methodology, 34 cyclic triaxial tests along with vane shear tests were performed on undisturbed mine tailings specimens from two impoundments in Kentucky. Therefore, the liquefaction resistance and the residual shear strength of the specimens were measured. The laboratory cyclic strength curves for the coal mine specimens were produced, and the relationship between plasticity, density, cyclic stress ratio, and number of cycles to liquefaction were identified. The samples from the Big Branch impoundment were generally loose samples, while the Abner Fork specimens were dense samples, older and slightly cemented. The data suggest that the number of loading cycles required to initiate liquefaction in mine tailings, NL, decreases with increasing CSR and with decreasing density. This trend is similar to what is typically observed in soil. For a number of selected specimens, using the results of a series of small-strain cyclic triaxial tests, the shear modulus reduction curves and damping ratio plots were created. The data obtained from laboratory experiments were correlated to the previously recorded geotechnical field data from the two impoundments. The field parameters including the SPT blow counts (N1)60, corrected CPT cone tip resistance (qt), and shear wave velocity (vs), were correlated to the laboratory measured cyclic resistance ratio (CRR). The results indicate that in general, the higher the (N1)60 and the tip resistance (qt), the higher the CSR was. Ultimately, practitioners will be able to use these correlations along with common state-of-practice geotechnical field methods to predict cyclic resistance in fine tailings to assess the liquefaction potential and post-earthquake stability of the impoundment structures.

Although there exist some consensus regarding seismic soil liquefaction assessment of free field soil sites, estimating the liquefaction triggering potential beneath building foundations still stays as a controversial and difficult issue. Assessing liquefaction triggering potential under building foundations requires the estimation of cyclic and static stress state of the soil medium. For the purpose of assessing the effects of the presence of a structure three-dimensional, finite difference-based total stress analyses were performed for generic soil, structure and earthquake combinations. A simplified procedure was proposed which would produce unbiased estimates of the representative and maximum soil-structure-earthquake-induced iv cyclic stress ratio (CSRSSEI) values, eliminating the need to perform 3-D dynamic response assessment of soil and structure systems for conventional projects. Consistent with the available literature, the descriptive (input) parameters of the proposed model were selected as soil-to-structure stiffness ratio, spectral acceleration ratio (SA/PGA) and aspect ratio of the building. The model coefficients were estimated through maximum likelihood methodology which was used to produce an unbiased match with the predictions of 3-D analyses and proposed simplified procedure. Although a satisfactory fit was achieved among the CSR estimations by numerical seismic response analysis results and the proposed simplified procedure, validation of the proposed simplified procedure further with available laboratory shaking table and centrifuge tests and well-documented field case histories was preferred. The proposed simplified procedure was shown to capture almost all of the behavioral trends and most of the amplitudes. As the concluding remark, contrary to general conclusions of Rollins and Seed (1990), and partially consistent with the observations of Finn and Yodengrakumar (1987), Liu and Dobry (1997) and Mylonakis and Gazetas, (2000), it is proven that soil-structure interaction does not always beneficially affect the liquefaction triggering potential of foundation soils and the proposed simplified model conveniently captures when it is critical.

In this thesis primarily structural induced liquefaction potential was aimed to be analyzed. Also the effect of base isolation systems both on structural performance and liquefaction potential was studied. FLAC software was chosen for the analyses so that structure and soil could be modeled together. By these means the soil structure interaction effects were also examined. Four different structures and three different sites were analyzed under two different input motions. All the structures were also analyzed as base isolated. It was mainly found that depending on the structural type and for a certain depth the liquefaction potential could be higher under the structure than the one in the free field. Also it was concluded that base isolation systems were very effective for decreasing the story drifts, shear forces in the structure and liquefaction potential in the soil. It was also found that the interaction took place between structure, soil and input motions.