Investigating the effect of material stiffness contrast on the dynamic stability of upstream tailings dams (Case study: Esfordi tailings dam)

The effect of mechanical properties of upstream tailings dams is investigated under seismic loads. For this, the finite-difference numerical method under the Finn-Byrne nonlinear elastoplastic constitutive model was implemented. Variations of elastic modulus and Poisson’s ratio in the typical range of tailings dam material were investigated in the phenomenon of liquefaction, horizontal displacement, and subsidence. The results showed that with increasing the elastic modulus of the dam body from 10 to 50 MPa, the maximum horizontal displacement, subsidence, and liquefaction coefficient in the dam body have increased 2.3, 3.5, and 2 times, respectively. Moreover, by increasing the Poisson’s ratio from 0.25 to 0.4, the maximum horizontal displacement, subsidence, and liquefaction coefficient in the dam body have raised 2.4, 2.3, and 1.75, respectively. The Poisson’s ratio of tailings had a significant effect on the liquefaction of the dam body. In which, increasing the Poisson’s ratio from 0.25 to 0.4, the maximum liquefaction coefficients were increased 1.75 times. Ultimately, it is concluded that despite the displacement which is not affected by the variation of tailings dam elastic modulus, the liquefaction coefficient is doubled by its variation, which may cause a serious threat to the stability of the dam.