The use of geosynthetic polymeric barriers in the impermeabilization of tailings dams concerns the designers about the performance of these materials under the high loadings these structures bear. Therefore, in this study, was evaluated numerically the interface between the dam material and, in a gold ore tailings dam in Brazil.

The tailings dam for which the study was conducted is built with the downstream method in a total of seven stages. The lining system was built using a textured high density polyethylene geomembrane with 1,5 mm width. The geotechnical parameters used for the model are found in Sampaio (2013) and refer to one of the cross sections at the third construction stage.

The use of a geomembrane in the foundation of the dam crest raises a concern about the possibility of ruptures of failure since the interface between the materials generates a potential slip surface between the underflow, used in the construction of the dam, and the geomembrane. This because the interface may represent a plane of low shear resistance between the liner and the structure, and consequently a plane of potential slide surface or of high deformability. Therefore, this study presents the results of a numerical analysis of interface shear stress tests conducted in the interface underflow-geomembrane, using the finite element software RS2, and analyzing different constitutive methods for the simulation.

It was observed that the Mohr-Coulomb constitutive model did not represent well the behavior of the experimental curve during shear, once the material did not present elastic-plastic behavior. It was also observed the sensibility of the model to the loadings. Finally, the influence of the boundary conditions in the presented simulation stands out, especially the use of a 2D model of a 3D problem and the resistance parameters of the materials used.