Numerical Modelling of Pb-Zn Mine Tailing Dam Based on Soil Stability

Mine tailings may cause important environmental problems. There are some tailing disposal methods which have been applied in the mining industry for a long time. Tailing dams that are generally used in the disposal of mine tailing also bring about many problems in terms of cost, environment and human health. In this study, a risk analysis of a tailing dam was carried out based on soil stability using the finite element method for a Pb-Zn tailing mine. Firstly, considering the topographic features of the tailing dam site, the geographical area of the dam was determined. Secondly, physical and geomechanical characteristics of tailing such as grain size distribution were determined in the laboratory by taking representative samples at various depths from different regions such as tailing and grounds of tailing dam. Lastly, by using this data, tailing area was modelled by finite element method and the distribution of stresses and displacements occurring in the tailing stream were shown. Risk zones of barriers have been identified in terms of stability. In addition, due to its location in the earthquake zone, the behaviour of dam against the earthquake loads was investigated and damages of dam were determined in a possible earthquake. Accordingly, the measurements carried out showed that maximum displacement and stresses in the dam spread from the tailing to the shed, when the duration of the earthquake is 3 s and 30° slope angle, the maximum displacement value for upstream design is calculated as 0.01 m and for downstream design as 0.05 m. For 35° slope angle, maximum displacement values have significantly increased by increasing the duration of the earthquake. This increase has been more limited for designs of 25° and 30°. Accordingly, it can be said that the border slope angle value is 30° in terms of seismic loads.