Abstract
The assessment of risk of static liquefaction of tailings storage facilities (TSF) has become a key topic in recent years. The stability of upstream-raised tailings dams relies on the strength of brittle, strain-softening tailings and therefore cannot
be analysed with standard limit equilibrium (LE) tools that do not account for progressive failure.
Finite element models (FEM), on the other hand, can capture the complete material behaviour, but require data that is usually unavailable during screening analyses at scoping study level. It is therefore convenient to use simple tools providing insight into the expected TSF behaviour before running full FEM models.
This paper describes a simplified procedure to analyse the stability of tailings storage facilities at screening level, employing a quasi-1D FEM model. NorSand critical state constitutive model was employed. The procedure allows for the simulation of the entire construction sequence, including raises at a prescribed rate and water content, evaporation and infiltration, consolidation, and time effects. At any time, a simple, static pushover analysis is used to assess the stability of the column and to identify weak points.
The proposed strategy reproduces the key features of tailings behaviour along the relevant stress paths, estimates the brittleness of tailings at various depths, and produces an assessment of the risk of static liquefaction for various deposition strategies and water flow scenarios. As is a completely automated procedure, it is possible to model any project, including variations in geometry, materials, deposition sequence, water flow conditions, etc.
