Dynamic compression failure and constitutive modeling of fully solid-waste cemented tailings backfill under impact loading

The growing emphasis on low-carbon and sustainable mining has intensified interest in alternative cementitious materials for cemented tailings backfill (CTB). However, the dynamic mechanical behavior of CTB incorporating fully solid-waste cementitious material remains insufficiently characterized. In this study, a fully solid-waste cementitious material composed of ground granulated blast-furnace slag, desulfurization gypsum, and fly ash was developed and applied to CTB. Using the glue-bone ratio, mass concentration, and average strain rate as variables, the dynamic compression tests were performed with a split Hopkinson pressure bar system to investigate the impact response of fully solid-waste cemented tailings backfill (FSWCTB). The strain-rate-dependent stress-strain behavior curves, dynamic compressive strength and failure morphology were analyzed, and the applicability of the Z-W-T constitutive model to FSWCTB was further evaluated. Furthermore, nuclear magnetic resonance and scanning electron microscopy coupled with energy dispersive spectroscopy were used to elucidate the microstructural features and hydration mechanisms of the FSWCTB material. Results indicated that (1) the dynamic compressive strength of FSWCTB increased progressively with higher glue-bone ratio, mass concentration, and average strain rate. (2) when the average strain rate increased to 415 s⁻¹, the failure mode of the FSWCTB specimens transitioned from localized collapse to global fragmentation. (3) The increase in glue-bone ratio and mass concentration led to the formation of a denser microstructure, which was beneficial for the development of backfill strength. The findings provide fundamental insights into the dynamic performance of FSWCTB and support its sustainable application in underground mining engineering.