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

## TL;DR

This study explores how water moves through fractured rock layers in a coal mine, revealing how pressure and fractures influence water flow.

## Contribution

The paper introduces a novel multi-scale analysis combining simulations and experiments to study water seepage and fracture propagation in coal mine overburden.

## Key findings

- Nonlinear pressure gradients increase flow velocities in dominant fracture channels.
- Higher injection rates expand effective channels by 86%.
- Erosion from high-velocity flow increases permeability and causes directional anisotropy.

## 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.