Application of an Advanced Constitutive Model in Nonlinear Dynamic Analysis of Tailings Dam

Tailings are residual material produced during the process of extraction of minerals from mined ores. Saturated tailings are usually retained in the impoundments by means of raised embankments (tailings dams). These are constructed in stages over the life of the impoundment with compacted natural soil, tailings materials and/or waste rock. Due to the usually huge dimensions of the impoundments, the great highs of the embankments and the site conditions like saturated loose granular foundation materials and high PGA, tailings dams represent a high-risk construction for the environment in case of a dam failure. In general, detailed numerical studies are conducted for seismic analyses of high-risk tailings dams during the design phase. However most of the analyses are performed using very simplistic stress-strain models such as Mohr-Coulomb model even for loose sand layers. For the present study, the SANISAND constitutive model was implemented in the finite difference code FLAC as a dynamic-link library. Then the liquefiable sand layer of a tailings dam under a seismic motion was analyzed using this more representative model. A number of representative results of the dynamic analysis including contours of shear strain and time history of the excess of pore pressure ratio for are presented and discussed. Results of the analysis suggest that at least for the analyzed motion the safety of the dam is not compromised.