Numerical analysis of strengthening by rockfill embankments on an upstream tailings dam

Abstract

The consolidation process could be slow in an upstream tailings dam; therefore, the stability can reduce due to an increase in excess pore pressures when the dam is raised. The safety of the dam can be enhanced by constructing rockfill berms on the downstream side. This paper presents a case study on the strengthening of an upstream tailings dam with rockfill berms. The finite element analyses were performed for modelling the staged construction of the dam and for optimizing the volume of the rockfill berms. The dam was raised in 11 stages; each stage consisting of a raising phase and a consolidation phase. The study shows that the slope stability of the dam reduced due to an increase of excess pore pressures during the raising phase. The stability of the dam was successfully improved by utilizing rockfill berms as supports on the downstream side. A technique has been presented to minimize the volume of the rockfill berms so that the required stability can be achieved at minimum cost. This paper shows that the finite element method can be a useful tool for modelling the consolidation behaviour of an upstream tailings dam and minimizing the volume of the rockfill berms that may be needed to maintain the stability of the dam during staged construction.

The Stability of Tailings Dams under Dry-Wet Cycles: A Case Study in Luonan, China

“…Numerical analysis has been widely used to solve complex issues about the slope stability of tailings dams [4,15,16]. Affected by rainfall infiltration, tailings recycling water, dry beach face evaporation, and other factors, the position of the phreatic line in the tailings pond suffers in various ways in the DW cycles [1,17,18].…”

“…The shear stress contour is one of the criteria for judging the sliding surface caused by instability of the tailings dam, and the area where the sliding surface is located is often the area where the value of shear stress changes significantly [15]. The shear stress of the numerical calculation model in Figure 5 after six DW cycles is shown in Figure 6.…”

Comparison of three dimensional and two dimensional axisymmetric finite element analyses of a corner section of a tailings da

“…For example, R2 ( Figure 9) indicates that this rock ll berm has been placed during the second raising. The volume of the rock ll berms, utilized in the present analyses of the corner, was adopted from another study performed by the authors on the straight dam section E-F [6]. The reason for using the same volume of rock ll is that both the dam parts, i.e.…”

“…It should be noted that there are some case studies about nite element analyses of tailings dams presented in the literature, (e.g., [6][7][8][9][10][11][12][13][14][15][16][17]. To the authors' knowledge, the validity of 2D axisymmetric analyses for a dam corner has not been addressed before.…”

Auscultation of a Dam for Mining Restoration in Quebec, Canada

“…The pore pressure (especially in muddy areas) will reduce the effective stresses and resistance to shear residues [6,7]. The static and seismic liquefaction are also considered a common cause of levees broke particularly those enhanced by the upstream method [8,9]. As the break is a physical process (mechanical, hydraulic), in general, the breakdown for embankments is made according to four classical mechanisms [10][11][12]: external erosion, internal erosion, external instability and liquefaction ( Figure 3).…”