A Two-Fluid Simulation of Tailings Dam Breaching

Abstract

This paper presents the development and application of a dam breach model, EMBREA-MUD, which is suitable for tailings dams. One of the common failure modes for these structures is breaching due to overtopping, which together with the flow of liquefied tailings, is simulated by the proposed model. The model simultaneously computes the outflow of water and tailings from a tailings storage facility and the corresponding growth of the breach opening. Tailings outflows are represented by a separate non-Newtonian viscous layer, which together with a water layer, represent the two fluid components of the model. The third component represents dam material that can be eroded by the shear forces exerted by either water or mud. The water layer also exerts dynamic and erosional forces and can transport solids eroded from either the mud or dam layer. The model was verified against laboratory cases as well as two field cases reported in the literature, the failures of the Mount Polley tailings dam in Canada in 2015 and the Merriespruit dam in South Africa in 1994. The model results agreed well with the recorded narrative of the events, although in the latter case, careful calibration of one of the model parameters was necessary to obtain a good match.

Modelling the Brumadinho tailings dam failure, the subsequent loss of life and how it could have been reduced

“…EMBREA-MUD is based on the EMBREA model, developed over a 20year period by HR Wallingford, which simulates embankment dam breaches and was first developed by Mohamed et al (2002) under the name HR BREACH and validated against a number of dam failures case studies including the Orós dam in Brazil in 1961, the Banqiao dam in China in 1975 (Morris, 2011) and the Teton dam in USA in 1976 (Mohamed et al, 2002). EMBREA-MUD predicts the growth of a breach in tailings dams via a range of processes, as well as the quantity of water and tailings released from the dam in the form of a hydrograph (Mohamed et al, 2002;Petkovšek et al, 2020). Both processes, breaching and outflowing, are simulated simultaneously based on the characteristics of the dam material, predicting the evolution of a breach opening without the need to make assumptions regarding the dimensions of the breach.…”

“…Both processes, breaching and outflowing, are simulated simultaneously based on the characteristics of the dam material, predicting the evolution of a breach opening without the need to make assumptions regarding the dimensions of the breach. EMBREA-MUD has been validated against two tailings dams failures, the Merriespruit tailings dam failure in South Africa in 1994 and the Mount Polley tailings dam failure in British Columbia in Canada in August 2014 (Petkovšek et al, 2020).…”

“…The last time the dam was raised was in 2013, and tailings disposal ceased in July 2016 (Robertson et al, 2019). The Brazilian Institute of Water Management of Mines (Instituto Mineiro de Gestão das Águas) and the National Mining Agency (Agência Nacional de Mineração) had evaluated and classified the dams probability of failure as being "low" (Porsani et al, 2019).…”

“…The ∼ 10 7 m 3 of tailings material flowed out of the Brumadinho tailings dam within about 5 min (Robertson et al, 2019). Information derived from a YouTube video of the event indicates that the maximum velocity of the mudflow may have been as high as 33 m s −1 (Petley, 2019). Three stills from the YouTube video of the dam failure, together with the local time at which they were taken, are shown in Fig.…”

Multiscale Investigations of Overtopping Erosion in Reinforced Tailings Dam Induced by Mud-Water Mixture Overflow

“…They also investigated the effects of three compacting conditions at the dam shoulder and toe. Beforehand, Petkovšek et al [19] extended the dual-fluid (water and tailings flow) model to the EMBREA dam failure model. At a much earlier stage, Bagnold [20] adopted a hydraulic test with a lightweight sand flume to observe the turbulence intensity variation in water flow during an erosion process, eventually concluding that the turbulence intensity significantly decreased by gradually increasing the sand content under a hydraulic condition of constant head.…”