Dynamic response characteristics of backfill under blasting disturbance simulated through a three-dimensional model

Abstract

During mining operations, the backfill body is subject to significant disturbance due to large-volume blasting, resulting in stress concentration and vibration response within the backfill. This alters energy distribution, leading to the continuous development, expansion, and accumulation of damage, potentially culminating in instability and collapse. Blasting disturbance in stopes is the main cause of filling instability and ore dilution. It is crucial to study the failure mechanism of filling bodies under blasting load to guide actual mine production. In this study, a custom mold was created to establish an innovative three-dimensional model of an ore-backfill system subject to explosion loading. Simultaneous detonation was selected as the control group and delayed detonation was selected as the experimental group. Monitoring and analysis methods, such as a high-speed camera system, MATLAB software, and vibration monitors, were utilized to investigate the impact of delay time on the dynamic response characteristics of the backfill. The results show that the dynamic fracture process of the backfill is mainly divided into four stages: initial crack initiation stage, crack development stage, crack expansion stage, and backfill collapse stage. The difference in delay time on the dynamic fracture process of the backfill is mainly reflected in two aspects: time effect and crack distribution. The surface flatness after delayed detonation is higher by 20.5 % as compared with that after simultaneous detonation. The average damping rate during delayed detonation decreases by 19.7 % as compared with that after simultaneous detonation, the frequency distribution of the single stage is more uniform, and the instantaneous peak energy during delayed detonation is 0.76 times that during simultaneous detonation. The maximum crushing size, average crushing size, and bulk crushing size after delayed detonation are reduced by 25 %, 15.26 %, and 9.23 %, respectively, compared with that after simultaneous blasting. Thus, delayed detonation effectively improves the crushing effect while reducing the degree of damage to the backfill.