Effect of seepage control on stability of a tailings dam during its staged construction with a stepwise-coupled hydro-mechanical model

Abstract

Seepage flow renders tailings dams vulnerable to failure during their staged construction. Draining is one of the most effective measures in improving dam stability. In this study, a stepwise-coupled hydro-mechanical model is employed to examine the effect of seepage control on the stability of a tailings dam during its staged construction. The settlement and deformation of the tailings under gravity load are modelled using the Duncan–Chang non-linear elastic E–B model, and the seepage flow through the tailings with drains is characterised by a variational inequality formulation of Signorini’s condition. The Kozeny–Carman equation is calibrated to illustrate the dependence of hydraulic conductivity on the porosity and volumetric deformation of the tailings. The proposed model was applied to assess the performance of the drains designed for the Luogou tailings disposal in Luanchuan County, Henan Province, China. Numerical results show that the stress-induced variation in tailings permeability could be of 1–2 orders of magnitude, and a proper design of the drainage system is of great importance in lowering the phreatic surface and protecting the tailings from seepage erosion.