Utilizing empirical and analytical rock-soil mechanics synergized approaches for tailings facility stability optimization

ABSTRACT: This paper focuses on the stability analysis of a Tailings Storage Facility (TMF) situated in the US, evaluating stability under static, seismically active, and post-earthquake conditions, following safety standards from the multiple global TMF guidelines. Designed with a geomembrane-lined valley-fill structure for dewatered tailings and a waste rock retention structure, this structure is planned to store approximately 52 million short tons of tailings produced in a 10-year period of life of mine. A discerning selection of waste rock fill was incorporated to enhance the stability, with multiple waste rock types tested to deduce critical parameters characterizing the rockfill. Using LEM software, slope section models of critical cross-sections were assessed, considering both unsaturated and saturated tailings parameters for conservative scenarios and liquefaction susceptibility. The downstream stability met the minimum required factors of safety, while side buttress stability required additional support, recommending a 25-foot buttress at higher elevations. This study is an example of an applied fusion of rock and soil mechanics to prevent probable low-stability TMF situations through robust design, real-time phreatic and deformation monitoring, and the future inclusion of site-specific liner strength testing.