Prediction of Pore Air and Water Pressure Propagation Induced by Extreme Rainfall in Tailings Dams

Simon Lorentz (First author), Charné Theron

Research output: Contribution to conferencePaperAcademic

Abstract

The stability of upstream deposited tailings dams is dependent on maintaining a drawn down phreatic surface and unsaturated profile in its outer edge. However, it has been speculated that intense rainfall events could induce unexpected translation of pore air and water pressures into the tailings profile and thus compromise the effective stress in the unsaturated zone or result in a sudden rise in the phreatic surface. This phenomenon, known as the Lisse effect, has been observed and studied in hydrological sciences to explain the rapid delivery of antecedent hillslope groundwater during storm events. However, the phenomenon has not been comprehensively applied to evaluating tailings dam slope stability. In this paper, the outcomes of controlled observations of the phenomenon in column and analytical experiments, are assembled and evaluated in terms of the surface water application volumes and rate, the properties of the porous media and the resultant nature of pore pressure and phreatic surface responses. In addition, application of applied theories to evaluate the rapid transmission of pore pressures through a profile in response to an advancing wetting front, leads to the development of a methodology that could be applied to tailings materials of a range of hydraulic conductivities and water retention characteristics. The theory is applied to a series of profiles of different tailings porous media, using varied water application rates. Resultant perturbations in phreatic surface elevation and changes to pore pressures in the unsaturated zone are used to evaluate changes in effective stress distribution in the unsaturated outer wedge and subsequent stability criteria. A possible evaluation algorithm for assessing stability criteria is suggested.
Original languageEnglish
Pages1883-1891
Number of pages9
Publication statusAccepted/In press - 2024
EventTailings and Mine Waste 2024 - Colorado State University, Colorado, United States
Duration: 10 Nov 202413 Nov 2024
https://www.thetailingsnetwork.com/tailings-conferences/tailingsminewaste2024

Conference

ConferenceTailings and Mine Waste 2024
Abbreviated titleTMW
Country/TerritoryUnited States
CityColorado
Period10/11/2413/11/24
Internet address

Keywords

  • tailings dams
  • extreme Rainfall

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