Hybrid Analytical–Numerical Calibration Framework for Surface Subsidence in Mountainous Multi-Seam Coal Mining

ABSTRACT: Traditional analytical solutions and prediction approaches for surface subsidence caused by underground coal mining generally assume horizontal or inclined coal seams with flat ground surfaces. This study developed and calibrated a two-dimensional FLAC3D modeling framework for predicting surface subsidence in mountainous, multi-seam inclined coal mining where traditional analytical methods failed to capture geometric and topographic complexity. To address this challenge, a numerical simulation framework using FLAC3D was developed and calibrated. The model procedure integrates comparisons with analytical solutions from the SEH (Subsidence Engineers' Handbook) method, influence function prediction methods, and field monitoring data. By integrating analytical insight, numerical simulation, and measured subsidence, this hybrid approach refines numerical parameters and enhances the reliability of subsidence prediction in inclined, multi-seam mining conditions. The calibrated model reproduced maximum subsidence within 2% of field data and captured asymmetric boundary behavior consistent with SEH and IFM predictions.