Effect of a vertical fracture on horizontal unsaturated seepage flow

The movement of water flow in unsaturated fractured rock was investigated with the sandstone sample through experimental research and numerical simulation. The experimental results show that the arriving time of wetting front is delayed by the fracture, resulting in the increase of water saturation in the domain on the upstream side of the fracture, which will locally enhance water flow through the matrix. The numerical simulation with the finite volume method captures effectively these characteristics. The comparison between simulated and observed travel time and arriving time of wetting front shows that their difference are very small and the simulated results are in agreement with the observed results, which implies calibrated parameters are reliable and effective. Then according to the calibrated parameters, fractured models were established to examine how the change of large fractured aperture would affect the arriving time of wetting fronts, pressure heads and water saturation on the upstream and downstream sides of fracture.