Deformation and failure characteristic of open-pit slope subjected to combined effects of mining blasting and rainfall infiltration

Abstract

Accelerated deformation and slope instability commonly occur within open-pit mines, indicating the action of potential triggering events such as mining disturbances or rainfall. However, limited studies have been conducted on the deformation behavior of open-pit slopes subjected to the combined effects of mining blasting and rainfall infiltration. This study proposes an integrated approach that combines satellite Interferometric Synthetic Aperture Radar (InSAR), coupled numerical analyses, and field monitoring for systematic evaluation of the deformation behavior and failure characteristic of a massive landslide that occurred on November 8, 2019 in the Qidashan open-pit mine, China. The InSAR data were reviewed aiming at characterizing the surface deformation fields over the mine site via small baseline subsets technique, as well as identifying unstable slopes and revealing their high susceptibility to mining operations and rainfall. Finite-difference modeling was performed to investigate the response mechanisms and factor of safety of the unstable slope, which were validated by using field data monitored with the global navigation satellite system. The simulation results indicate that the Qidashan landslides were triggered by intense rainfall causing a gradual reduction of shear strength, and mining activities promoted failure by providing stress relaxation and blasting disturbance. Furthermore, this study contributes critical insight into the identification of deformation and early warning of unstable slopes in frequent mining environments, and allows for a back-analysis of the failure mechanism of landslide reactivation. This study highlights how important it is to account for the combined effects of mining and rainfall infiltration when assessing the stability of open-pit slopes, which can mitigate the failure risk.