Meso-scale modeling of the influence of waste rock content on mechanical behavior of cemented tailings backfill

Abstract

The solid waste disposal technique, known as cemented tailings-rock backfill (CTRB), has been increasingly picking up interest in underground mining due to its capability of managing tailings and waste rock simultaneously. However, the mechanical response of CTRB is still not well understood. In this study, 2D meso-scale models are established to evaluate the mechanical behaviour of CTRB with a specific focus on the effect of waste rock content under compressive and tensile loadings. The cemented tailings backfill (CTB) matrix, waste rock aggregates, and the interfacial transition zone (ITZ) between them are explicitly established in the meso-scale model. The results demonstrate that as the waste rock content increases, CTRB performs more brittle in conjunction with a lower strength and a higher Young’s modulus under uniaxial compression, and the stress distribution and crack pattern become more fluctuant and complicated. The uniaxial tensile behaviours of CTRB models with various waste contents are very similar, even though fluctuation is observed among their tensile strengths. Multiple micro-cracks initiate from the ITZ, then propagate to the matrix and coalesce to form the macro-cracks at the post-peak stage, regardless of loading scenarios. In addition, both the compressive energy and tensile energy absorbed by the matrix decrease, but that absorbed by ITZ and waste rock increases, with increasing the waste rock content. It is anticipated that the simulation results will contribute to the design of better and superior failure resistant backfill materials and structures and be a starting point for more sophisticated meso-scale models of CTRB.