Damage characteristics and constitutive model of magnesium slag-based cemented backfill based on energy dissipation

Abstract

Uniaxial compression tests were conducted on magnesium slag-based backfill with different curing ages (3, 7, and 28 d) and different magnesium slag grinding time (0, 40, 60, and 80 min) to investigate the energy damage characteristics and the constitutive model of ground magnesium slag-based cemented backfill in depth. The effects of curing age and magnesium slag grinding time on the energy evolution and distribution characteristics, as well as energy indexes at characteristic points of magnesium slag-based backfills, were examined. From the perspective of energy dissipation, damage variables and modified damage constitutive models were proposed to address the shortcomings of existing damage constitutive studies. The results of the study show that extending the curing age can effectively increase the energy storage limit of backfill and exhibit higher linear elastic deformation capacity. The elastic energy ratio curves of the backfill show an upward and then a downward trend, while the dissipated energy ratio curves show the opposite trend. The relationship between the total energy at the peak stress and the curing age and magnesium slag grinding time can be characterized by linear and quadratic polynomial functions, respectively. The pre-peak energy consumption, post-peak energy consumption, total energy consumption, and energy storage limit of magnesium slag-based backfill all show a linear increase with increasing curing age. The modified energy damage constitutive of magnesium slag-based backfill considering the compaction stage and residual strength shows higher consistency with the test constitutive, which can more realistically reflect the deformation process of the backfill. These results can provide a theoretical basis for investigating the stability of magnesium slag-based backfills in mine filling applications.