Excavation-induced open-pit slope failures behaviors from microscopic insights using DEM analysis

Abstract

Excavation-induced slope failures present critical challenges in open-pit mining engineering yielding various failure morphologies, yet the underlying the mechanisms remain insufficiently understood. This work attempts to investigate slope arching failures induced by progressive excavation by employing a multi-scale approach integrating Discrete Element Method simulations and analytical solutions. The combined findings reveal a dominant role of initial material packing density in governing slope failure morphology: densely-packed slopes develop well-defined stress arching with localized deformation and delayed collapse, whereas relatively-loose slopes exhibit early, global failure with minimal stress reorientation. Furthermore, the microscopic densitydependent stress redistribution and rotation of principal stress trajectories have been quantitatively evaluated in both physical model tests and numerical models. In addition, a novel classification criterion based on incremental displacement ratios is proposed for distinguishing different failure phases, offering a more reliable indicator of failure onset compared to traditional accumulated displacement metrics. The findings provide micromechanical insights and interpretation into macroscale slope behavior, thus enhance the current understanding of realistic failures in excavation-affected open-pit slopes.