Dynamic mechanism triggering the catastrophic Xinjing Landslide in Alxa, Inner Mongolia, China

Abstract

Few studies have been conducted on the deformation and failure behaviors of open-pit slopes exposed to the combined impacts of mining blasting and geostructure, particularly those generated purely by mining blasting. This study proposes an integrated approach, specifically including dynamic modeling using a novel mesh generation strategy, to systematically reveal the progressive deformation, critical failure and long runout of a catastrophic landslide that occurred on 22 February 2023 at the Xinjing open pit mine, Inner Mongolia. The results show that the internal factors responsible for the landslide include lithological setting, micro-landform, geological structure, and rock mass structure. An unidentified pre-existing reverse fault served as the key internal factor. On the other hand, the external trigger for the landslide was the blasting operation near the slope foot, which exacerbated the fragmentation and ultimately led to the critical failure and overall slide along the fault plane. The landslide manifested as an advancing rock wedge slide. The failure initiated from the back and then the middle parts of the original slope, which pushed the front and foot to trigger the subsequent creep. The following runout was controlled by the topographic relief of the open-pit bottom and consisted of five stages: critical failure, disintegration and fragmentation, debris avalanche, collision and surging up, and accumulation and self-stabilization. Finally, the blasting vibration was identified as the sole trigger for the Xinjing landslide, which had been subjected to the prolonged impact of the reverse fault. This study highlights how important it is to account for the sole effect of mining blasting when assessing the stability of open-pit slopes, which can mitigate the failure risk.