Modelled active-mining and observed post-closure deformation in a mountainous coal mine: a 3DEC-InSAR case study from Xinjiang, China

Active mining and post-closure ground deformation are often examined separately, and their linkage remains poorly constrained in loess-covered mountainous terrain, where topography can amplify geohazards. We integrate 3DEC discrete-element simulations, SBAS-InSAR monitoring, and field investigations at a closed coal mine in Xinjiang, China. The analysis combines a simulated active-mining phase with a separate post-closure observation period beginning approximately two years after mine closure, characterizing two distinct stages rather than a continuous field-observed lifecycle. Three site-specific patterns emerge. Residual settlement continues after reclamation, supporting long-term monitoring. Deformation also varies with landform and material conditions: simulations show greater vertical movement in gullies and thicker loess, whereas slopes exhibit stronger lateral movement, step-like fissures, and landslide morphology in the field. The spatial correspondence between subsidence features and slope failures is consistent with a conceptual subsidence-slope-instability pathway, while the observations cannot resolve temporal precedence, infiltration-driven acceleration, or landslide probability. During excavation, simulations indicate stress redistribution, asymmetric bending, and upward deformation through the layered materials. These results provide case-specific evidence for deformation assessment and post-mining land-restoration planning.