Assessment of interaction between a waste storage dam and instability in downstream right-side slope by 3D numerical analyses

Waste dams (tailings) are used for storing the byproducts of mining operations and are very common in the mining industry. As the material they are storing can be harmful to the environment and the people in the vicinity, the construction of these dams is of high importance. During the construction phase, the topography of the site and geological–geotechnical parameters of the soils around the dam are as important as the stability and the leakage issues of the main dam body. In this paper, a nickel-ore waste dam located in Manisa-Gördes, Turkey is investigated in detail by 3-dimensional (3D) finite-element analyses. At the downstream side of the dam, there was slope instability at the right-hand side slopes due to improper loading on the top of these slopes. Whether this slope failure will affect the stability of the main dam body or not is the main question of this study. Within these confines, 3D finite-element analyses that cover a large area, including the dam, upstream and downstream sides, and the waste have been performed before and after the planned downstream slope rehabilitation. The main rehabilitation methodology employed in this study is the removal of the displaced material and re-shaping of right-hand side slopes. The results show that after the rehabilitation of the slopes, the deformations decreased considerably, and the waste dam became safer. Consequently, the study presents an interesting case study including the interaction between waste storage dam and side-slope instability with 3D finite-element analysis. At present, the planned slope excavations and the dam body construction were completed successfully.