Experimental Study of yield surface of saturated silty tailings

Articles in Press

Document Type : Article

Authors

1 PhD student, Faculty of Engineering, Department of Civil Engineering, Ferdowsi University of Mashhad

2 Ferdowsi university of mashhad

10.24200/j30.2024.64136.3306

Abstract

Static liquefaction is one of the most important challenges for the stability of mining tailings dams. Several experimental studies have been conducted on this issue within the framework of critical state theory. Additionally, deformations such as tensile cracks and unusual static deformations of these dams are among the other issues related to the stability of these structures. Numerical simulation of the stress-strain behavior of materials under various loading conditions requires a suitable constitutive model, with one of its main components being the yield criterion. Extensive studies have been conducted to identify the yield surfaces of soil materials (sand and clay) through laboratory tests, but the identification of yield surfaces for tailing materials has received less attention. This study aims to identify the yield surface of silty tailing materials from the Sungun copper mine using laboratory experiments under initial isotropic stress and saturated conditions. For this purpose, all specimens with a similar stress history were initially consolidated under isotropic stress conditions and then unloaded up to 50% of the initial confining stress. The overconsolidation ratio (OCR) of these specimens was approximately set to be two. Subsequently, the specimens were subjected to stress-controlled radial stresses in the effective mean stress-deviatoric stress (ṕ-q) space. The compatibility of the laboratory yield surface with the proposed yield surfaces of the Mroz constitutive model was examined. The results indicate that the obtained yield surface under existing stress conditions follows the non-associated flow rule. The proposed yield surface of the Mroz constitutive model, by considering appropriate constants, shows satisfactory agreement with the laboratory yield surface. The work input for each stress path demonstrates that at approximately 0.25 kJ/m2, the specimens reached yield conditions. The flow vector plots indicate that the obtained yield surface follows the non-associated flow rule. Observing linear trends in the deformation changes of the specimens after the yield point indicates rapid cementation in these materials.

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Sharif Journal of Civil Engineering

Articles in Press, Accepted Manuscript
Available Online from 12 May 2024

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