Dynamic Analysis of an Upstream Tailings Dam

A number of tailings dam failures around the world have raised many questions upon the stability of tailings dams. Due to this over the last few decades stability of tailings dams have drawn much more attention. The failure of a tailings dam may results into the release of the stored tailings in the surrounding locality. In most of the cases, the damage has occurred as a result of large reduction instiffness and strength of soil, which ultimate might result in dam liquefaction. Earthquake is one of the big triggering source of liquefaction. To reduce such damages of tailings dams, a detailed method of seismic analysis is very essential. In this thesis, dynamic analysis of an upstream tailings dam is presented. Dynamic analysis was performed by using the finite element method. The Aitik tailings dam, located in the northern part of Sweden was selected to perform a dynamic analysis. A constitutive material model UBCSAND was used for tailings. UBCSAND is based on the elastic-plastic stress strain model proposed by Byrne et al. (1995). This model has successfully been used for the liquefaction analysis. The finite element program PLAXIS was used for the determination of deformations and excess pore pressures which are generated as a result of earthquake loading. The excess pore pressure ratio criterion was used for the liquefaction assessment. On the basis of excess pore pressure ratio values for the tailings dam, it was concluded that in an Extreme case (Mw=5.8) earthquake, liquefaction is likely to occur at a small section of the dam (below the surface near the Embankment dikes). The predicted displacements due to earthquake were tolerable and freeboardallowance was suggested by using the deformation values.Validerat; 20130930 (global_studentproject_submitter