Numerical Analysis of Unsaturated Seepage Flow in Two-Dimensional Fracture Networks

Abstract

Fracture-dominated flow in fractured rocks is of interest in many areas of scientific and technical research. In contrast to the continuum approach, this study employed a discrete fracture model method to analyze water movement in unsaturated fractured rocks, in which the flow behavior for single fractures is governed by Darcy’s law and the Richards equation, and the partial differential equations defined on the whole fracture network domain were formulated. A systematic finite-element algorithm was developed along with a corresponding numerical procedure. The results for the porous medium indicate that the proposed method is valid. Good agreement was found between the numerical predictions and experimental observations, and thus the equivalent discrete fracture network model may be used in place of the continuum model. The infiltration seepage analysis in a fractured rock slope demonstrated that the distribution of fracture-dominated flow was heterogeneous and that the movement of variably saturated seepage flow was substantially influenced by the orientation of fractures.