Influence of the Presence of Frozen Tailings Layers on Pore Water Pressure and its Management in Dam Stability

January 7, 2026

Winter deposition of tailings at facilities located in cold climates can lead to the formation of frozen layers. Over multiple winter seasons, multiple frozen layers can develop within the tailings. These frozen layers can affect the pore pressure distribution within the tailings by acting as aquitards due to their low permeability, restricting vertical seepage and forming perched water tables above them. The resistivity cone penetration test (RCPTu) has been demonstrated to be a useful method for identifying the presence of frozen layers. Pore water pressure (PWP) conditions below frozen layers can be sub-hydrostatic, meaning that the pressure in the pore water is lower than would be expected based on the height of the overlying water column. In some tailings layers located between frozen layers, the tailings may even have zero pore pressure, which leads to the formation of an unusual, zig-zag pore pressure pattern with depth below the phreatic surface. This phenomenon can create challenges in the evaluation of the dam stability, as the expected pore pressures may not align with traditional assumptions. This study examines the impact of frozen tailings layers on PWP within the Aitik Tailings Management Facility (TMF) in Sweden. Analyses are presented that cover multiple scenarios for the frozen layers, including variations in the quantity, location, and thawing of these layers.

Yauli, C., Chiu, C., Shire, T., Cooper, D., Girard, R. 2025 "Influence of the Presence of Frozen Tailings Layers on Pore Water Pressure and its Management in Dam Stability,” in Proceedings of the Tailings and Mine Waste 2025 Conference, 2-5 November 2025, Banff, Alberta: University of Alberta Geotechnical Centre (UAlbertaGC) (CGS and CPA)