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Preliminary Analysis of the Failure Process of a Tailings Dam

Tailings and Mine Waste Conference (2023 : Vancouver, B.C.); University of British Columbia. Norman B. Keevil Institute of Mining Engineering

Motivated by recent high-profile tailings storage facility (TSF) failures around the globe, the tailings and mine waste community is actively working to identify potential triggering mechanisms for those tragedies. Case histories are a valuable resource to understand triggering mechanisms. This paper presents a preliminary analysis of a tailings dam failure that occurred over two decades ago, which released about 283,000 cubic meters of tailings and non-mineralized mine rock along a 274-meter-long section of the westfacing slope. The released mass flowed downstream for about 610 meters. The failure took place at a location where waste rock was being placed on top of tailings. Specifically, the rapid placement of a second 15-meter lift of waste rock likely led to an undrained failure in the tailings due to a lack of time for excess porewater pressure (PWP) dissipation. In this study, limit equilibrium (LE) analysis was adopted. Excess PWP within the tailings before the triggering of the failure was taken into account by assigned B-bar values. In addition, a LE analysis strategy considering strength reduction and failure surface evolution (from a local rotational shear failure to a global breach) was performed to understand the progression of the failure. Analysis results highlighted the following two key aspects: (1) the failure was correctly captured through LE analysis when the drainage conditions, or the excess PWP, was well quantified; and (2) a reasonable progression of the failure can be verified through LE analysis considering strength loss in the tailings. These findings affirm the capability of the LE analysis despite its simplicity. Furthermore, this study provides a valuable case to expand the current case history-based liquefaction flow failure database.

Text

2023-12-08

Attribution-NonCommercialNoDerivatives 4.0 International

http://hdl.handle.net/2429/86808

Unreviewed

http://creativecommons.org/licenses/by-nc-nd/4.0/