Study on the nonlinear deformation characteristics and constitutive model of cemented tailings backfill considering compaction hardening and strain softening

The deformation characteristics of the cemented tailings backfill (CTB) has a significant influence on the stability of mine stope and surface subsidence after filling mining. An uniaxial compression experiment of the CTB containing different cement-tailings ratios (c/t) has been performed and it shows that the CTB has an obvious compaction hardening in the initial compaction stage and strain softening at the plastic yield stage. However, these nonlinear deformation characteristics of CTB are not fully understood in the previous studies. In this research, considering the nonlinear deformation characteristics, a complete constitutive model was proposed for the CTB based on the experimental stress-strain curves. This constitutive model has been programmed into FLAC3D to obtain the law of surface subsidence and assess the safety of the concentrator if the backfill method is adopted. In addition, a physical model experiment of filling mining is also carried out at the same condition. The results of these two simulation experiments show that the surface subsidence is negatively correlated with the distance between the concentrator and the collapse pit, and the maximum subsidence is less than 90 mm. Therefore, the filling mining method can effectively guarantee the safety of concentrator. This study provides a better understanding of the deformation characteristics of CTB and it also contributes to the underground filling technology of using CTB. (C) 2022 The Author(s). Published by Elsevier B.V.

Automated summary

The deformation characteristics of cemented tailings backfill (CTB) and its implications for mine stope stability and surface subsidence were studied. A complete constitutive model was proposed based on experimental stress-strain curves to describe the nonlinear deformation characteristics of CTB. Simulation and physical model experiments were conducted to assess the safety of the backfill method. Results showed that the backfill method effectively ensured the safety of the concentrator.