SOLD OUT - Procedure for Assessing the Liquefaction Vulnerability of Tailings Dams

It is common practice to deposit tailings hydraulically into upstream-raised tailings storage facilities (TSF) whose stability depends on the strength of the tailings themselves. Due to the tailings deposition method, upstream-raised tailings dams are vulnerable to flow liquefaction.

As a result of recent tailings dam failures (Cadia, Samarco, Brumandhino), the current practice of stability assessment of tailings dams is to assume that all materials susceptible to flow liquefaction will liquefy. It is recognized that evaluating all possible triggers for flow liquefaction is not practically feasible, and that triggering analyses are not frequent at the stage of the design process of a new dam.

This work presents a procedure for assessing the liquefaction vulnerability of tailings dams system (including the retention structure, retained materials and foundation). The proposed procedure tests the system resilience by employing a set of deteriorating events that may result in the instability of the system, rather than identifying plausible failure scenarios. The procedure employs a numerical deformation model to reproduce the conditions of a dam after construction and applies a set of actions aimed at mobilizing the shear strength of the tailings under undrained loading conditions to check for progressive failure and instability. The procedure was tested by applying it to the well-documented Fundão Dam failure.

The validation carried out in this work illustrates that the proposed procedure, using currently available modelling and numerical tools as well as standard laboratory and field characterization, can be an useful tool assess the susceptibility of tailings dams failure due to flow liquefaction.

About the Presenter:

Osvaldo is a Principal Consultant in the Geoenvironmental Engineering Division of SRK Canada. He is a Civil Engineer graduate and PhD candidate from the University of Buenos Aires, Argentina, with over 12 years of experience in geotechnical engineering for infrastructure and mining.

He has been involved in the design of foundations, large excavations, tunnels, earth embankments, and dams for civil infrastructure and mining projects. His experience includes field investigation, construction oversight, and detailed engineer design. He has advanced knowledge in the application of numerical methods for modeling soil behavior under static and seismic conditions. Osvaldo also facilitates waste management decision-making and risk assessment sessions for industry and stakeholder groups