Highly heterogeneous mining waste soil characterization with 3D linear elastoplastic FEM model

The recyclability of wastes, especially mining waste, is one of the current challenges. Mines are subject to a well-defined life cycle planning to allow sustainable exploitation and development for the next generations. Mining techniques have developed considerably, so mining waste has become highly concentrated on pebbles. To build embankments and spoil heaps, it is necessary to know the mechanical properties of the composite mixture forming the mining waste. This paper tackles the calculation of the mechanical properties of highly heterogeneous mining wastes using a linear elasticity homogenization approach. Numerical models based on the finite element method are developed to determine the elastoplastic properties of the mixture. A first model enables the calculation of the Young’s modulus and the Poisson’s ratio of the mixture; then, based on an identification technique, a second model calculates the Mohr–Coulomb plasticity parameters. The obtained results show that the mixture is isotropic, and the mixture rigidity increases when the pebble concentration increases from 10 to 50%. Conversely, the volume maneuverability displayed by the Poisson’s ratio decreases when the pebble concentrate increases. For the identified coefficients using Mohr–Coulomb model, the cohesion decreases from 9.13 to 5.59 kPa when the pebble concentration increases from 10 to 40%. The cohesion of the mixture remains higher compared to the cohesion of the limestone up to a concentration of 40%; it becomes 3.58 kPa. The mixture friction angle is always higher than the limestone friction angle.