Modeling Study on Cumulative Damage Effects and Safety Control Criterion of Open-Pit Final Slope Under Blasting

Drilling and blasting method used for excavation causes damage to surrounding rock mass, and frequent blasting often leads to cumulative damage effects. Thus, understanding the distribution of Blast-Induced Damage (BID) zone is critical to assess the slope stability of open-pit mines. Herein, this study aims to investigate the cumulative damage effects and safety control criteria on the final wall of the open-pit slope under blasting. The cumulative damage zone was defined using a continuous damage model coupled with tensile damage and Drucker–Prager yield criteria embedded in the finite difference method. The simulation results were validated against field data collected from the Wushan open-pit mine in Inner Mongolia, China. The results demonstrate that the cumulative damage of the final wall exhibited a non-linear decreasing trend from the bench face to the interior of the slope, successfully reproducing the spatial distribution of the BID obtained from the in situ test, and revealing that the maximum cumulative damage depth occurred at the slope crest. Additionally, a safety control criterion for the critical damage zone of open-pit final slope was proposed based on the investigation of the effects of dynamic loading rate and stemming length on excessive overbreak. The results highlight how important it is to account for cumulative damage effects when assessing the final slope stability of an open pit and optimizing the mining design. Highlights The cumulative damage effects on the final wall of the open-pit under blasting are investigated. A model coupled with tensile damage and Drucker-Prager yield criteria is established and incorporated into finite difference method to simulate the blast-induced damage zone. The subsurface damage depth is obtained using the digital drilling images technology. The dynamic loading rate and stemming length could significantly affect the excessive overbreak along the crest.