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Abstract

Synthetic rock mass (SRM) models commonly represent fractures as planar surfaces, potentially oversimplifying the complex geometries observed in natural rock masses. This study investigates whether incorporating large-scale fracture undulations significantly affects predicted rock-mass strength compared to conventional flat joint representations. Using the Finite-Discrete Element Method (FDEM), we analyzed multiple discrete fracture network (DFN) configurations under uniaxial and biaxial loading conditions, comparing models with geometrically simplified planar fractures against those incorporating conceptual undulated surfaces. Results reveal counterintuitive and inconsistent patterns across different DFN geometrical realizations, demonstrating that network topology and connectivity patterns govern overall behaviour more than individual fracture geometry. These findings challenge assumptions that geometric simplification can be systematically compensated through parameter adjustments. However, given that detailed fracture characterization data are typically unavailable until design completion, and even accessible rock outcrops provide only limited 2D surface exposures of inherently 3D fracture networks, pursuing sophisticated geometric representations may be impractical. Instead, engineering practice should focus on quantifying inherent variability bounds.