Study on the Size Effect of Fracture Intersections Based on the Fractal Theory

The geometrical complexity of the fracture space in a rock mass makes the study of the seepage characteristics of fractured rock masses very challenging. Therefore, the study of size effect of fracture intersections, which is the basic fracture shape of fractured rock, can guide the research of fracture seepage. In this context, this paper used FLUENT software to perform a two-dimensional numerical analysis of seepage characteristics at fracture intersection of nine different sizes and analyzed the effect of the intersection size on the fluid pattern and its fractal dimension and split-flow characteristics. The results show that, on the whole, the fractal dimension of the fluid pattern first increased and then decreased, then increased and decreased again with the flow of fluid. The critical point that determined whether fluid would flow out of horizontal fractures was a/b = 0.15; beyond this value, fluid would flow out of three pressure outlets, with flow out of horizontal fractures being higher than out of longitudinal fractures. a/b = 7 was the critical point that determined whether fluid would flow out of longitudinal fractures; at greater values, fluid would flow out of both horizontal fractures and would be far greater than longitudinal flow.