Abstract: The existence of the representative elementary volume (REV) is a prerequisite for using the equivalent continuum methods. This paper utilized the geometric parameters of fractures collected from the Three Gorges Project and conducted 20 random simulations of fractured rock masses using the Monte Carlo method. A numerical model of fractured rock masses was established based on COMSOL Multiphysics. Different-sized computational domains (ranging from 6 to 70 m with a 4-m increment) were extracted from the generated geometric model of fractured rock masses. The permeability values of fractured rock masses of different sizes and the variation pattern of permeability REV with changes in fracture aperture were calculated with and without consideration of matrix permeability. The research findings indicate that when matrix permeability is not considered, REV is independent of fracture aperture; when matrix permeability is considered, REV tends to increase with the enlargement of fracture aperture. In cases where matrix permeability is considered and fracture apertures are small, the fracture network tends to behave as a homogeneous medium with a small REV. As the fracture aperture increases, the heterogeneity of the flow field becomes stronger, and REV also increases. This study expands the range of equivalency for fractured rock masses and provides reference for studying fluid flow in fractured rock masses when considering matrix permeability.
Keywords: fracture network; fracture matrix system; scale effect; representative elementary volume (REV); permeability
合肥工业大学学报自科版