Experimental Investigation of Stress-Induced Anisotropy on the Yield Surface of Mine Tailings

Numerical simulation of the stress-strain behavior of materials under various loading conditions requires an appropriate constitutive model, with the yield surface being one of its key components. Extensive studies have been conducted to identify the yield surface of soil materials (sand and clay) through laboratory methods. However, the identification of the yield surface of waste materials has received less attention to date. Waste materials are artificial soil-like substances produced during the crushing and concentration processes in mineral processing plants. In this paper, a laboratory program was carried out using an advanced triaxial stress-path and stress-control apparatus on reconstructed saturated samples from the Sungun mine, located in the northwest of Iran. These samples were reconstituted using the wet tamping method. Through analysis and interpretation of the results, the yield surfaces of these lightly over-consolidated materials, with both isotropic and anisotropic initial consolidation conditions, were determined. The dependency or non-dependency of the obtained yield surfaces was evaluated, and the effect of consolidation stress and the angle of the applied stress path on the variation trends of the secant shear modulus and secant bulk modulus-indicating structural anisotropy of the waste materials-were assessed. Finally, the structural anisotropy of the samples was examined using SEM images and statistical processing of particle orientation and a mathematical model for the obtained yield surfaces was proposed.