Aznalcóllar dam failure. Part 3: Dynamics of the motion

Abstract

The motion of the Aznalcóllar dam slide, after the initiation of the failure, is examined in the paper. The moving mass remained essentially rigid, and Newton's second law provides the basic equation to determine the resulting dam displacement, velocity and acceleration. Resisting forces have been derived from a previous analysis of the conditions leading to failure. Pore water pressures induced by the forward motion of the dam are approximated as an undrained loading of the clay. Driving forces and their evolution in time derive from the liquefaction of tailings and the condition of constant volume of liquefied tailings pushing the moving dam forward. The stable 'cliff' left by the motion inside the tailings lagoon supports this hypothesis. The model is able to reproduce closely the distance travelled by the dam. It shows a low sensitivity with respect to reasonable changes of the main parameters. The model computes that the slide motion lasted about 15 s, and that the maximum acceleration experienced by the dam was 0 . 14g.

Revisiting the Hydraulics of the Aznalcóllar Mine Disaster

“…4e); thus, this value being the pond crest for the whole pond perimeter, the spilled volume could potentially reach 15.4 hm 3 . Nevertheless, according to Alonso and Gens (2006a), the water level was 4.4 m below the crest during the day before the failure; thus, the maximum spilled volume would be 9.3 hm 3 . Both presented and calculated values are within the volume that was potentially stored in the pond.…”

Effects of the foot evolution on the behaviour of slow-moving landslides

“…When the sliding mass keeps its basic shape, the analysis is much simpler and the motion of a rigid block can be simulated using a single dynamic equation. The initial model was proposed by Heim (1932), but there are many recent examples involving further developments: a viscous term was incorporated by Angeli et al (1996) and Corominas et al (2005), and also an interaction between two blocks was considered in a particular case by Alonso and Gens (2006). In fact, the idealization of a landslide as a set of several interacting blocks was proposed by Picarelli et al (2004) and seems to be a promising modelling strategy.…”

Application of a critical state model to the Merriespruit tailings dam failure

“…at a weak foundation layer), static liquefaction of tailings does much to aggravate the failure, as seen in the cases of Aznalcollar (a.k.a. Los Frailes) (Alonso and Gens, 2006) or Cadia (Jefferies et al, 2019). Static liquefaction of tailings is possible if the tailings are deposited loose and remain saturated: these are frequently occurring features of the upstream construction method.…”