The Effect of the Material Spatial Variability in the Slope Stability of Sand Tailings Dams

Given Chile's status as one of the main copper producers in the world, it is essential to protect critical geo-infrastructure related to the mining industry, such as tailings dams. Tailings, the residual materials from mineral extraction, consist of ground rock, unrecovered metals, and chemical byproducts. The rising global demand for minerals has escalated large-scale mining activities, producing vast volumes of tailings,which are impounded by large embankmentsand sandtailingsdams, where static and seismic slope stability analyses are crucial to prevent catastrophic failures, such as the Brumadinho dam collapse in Brazil, which caused 259 fatalities and severe environmental damage. The slope stability of tailings dams is typically evaluated using the factor of safety (FS), defined as the ratio of resisting to driving forces, and the critical seismic coefficient (k_y) from seismic analyses targeting an FS of 1.0. Such analyses are commonly conducted using deterministic approaches, which often overlook significant uncertainties.Probabilistic methods have gained interest in the industry toaddress uncertainties in slope stability analysis of tailing dams but generally disregard the spatial variability of geotechnical properties in large geostructures, assuming soil homogeneity. Nevertheless, factors such as material deposition, compaction, and construction processes in tailings dams significantly influence the spatial variability of geotechnical properties, thereby affecting slope stability analyses. This study evaluates the impact of spatial variability on the slope stability of tailings dams by incorporating inherent uncertainties using random fields derived from in-situ cone penetration tests (CPTu)(CPTu) data. The findings highlight the influence of spatial variability on FS and k_y, providing a foundation for ongoing research that will further investigate its impact on seismic performance of tailings dams.

Keywords: Geotechnical uncertainty, Spatial variability, Tailings dams, Slope stability, Random fields, Probabilistic analysis.