Mechanisms of stress distribution influenced by numerical model size and goaf parameters in multi-coal seam mining

Multi-seam coal mining often leads to complex stress redistribution due to strong interlayer interactions. This study employs FLAC3D to investigate the influence of numerical model dimensions and goaf constitutive representation on stress distribution in multi-seam mining. Key factors considered include model thickness, roof caving angle, and the choice between Null and Double-Yield (D-Y) models for goaf simulation. Results indicate that smaller model thicknesses amplify stress concentration near goaf edges due to boundary effects, although this sensitivity diminishes when more than three seams are mined. While numerical model size has minimal impact on the location of stress peaks, it predominantly affects the magnitude of stress concentration. In contrast, the choice of goaf constitutive model plays a key role in controlling stress peak location, with the D-Y model providing a more realistic representation of stress transfer through compacted goaf zones compared to the Null model. Additionally, increasing the roof caving angle in the D-Y model facilitates the upward migration of stress concentration toward overlying strata. These findings underscore the importance of selecting appropriate goaf models based on geological conditions and clarify the distinct roles of model size and goaf representation in governing stress magnitude and stress peak location. The study offers valuable guidance for accurately simulating stress redistribution and enhancing the design of coordinated multi-seam mining operations in complex geological environments.