Fracture propagation and water seepage behavior in overburden strata at Tunbao coal mine

Abstract

Abstract This study investigates water inrush mechanisms in goaf roof strata through multi-scale analysis of fracture network evolution and seepage dynamics. A three-zone overburden model was established via PFC3D simulation and validated with experimental data. Coupled PFC-CFD simulations reveal that seepage is governed by the interplay of pressure gradients, fracture pathways, and flow rates. Key findings include: nonlinear attenuation of pressure gradients amplifies flow velocities in dominant channels; increased injection rates widen effective channels by 86%; and high-velocity flow enhances permeability through erosion, resulting in significant directional anisotropy. These results provide insight into the positive feedback mechanisms controlling dynamic seepage in fractured rock masses.