A discrete fracture network model for geometrical modeling of cylindrically folded rock layers

Geometrical characterization of discontinuities is a crucial step in determining the mechanical and hydraulic properties of rock masses. Discrete fracture network models are developed to model the geometric properties of discontinuities using the statistical distributions of these properties measured from core logging and outcrop mapping analyses. Among all of the discontinuity properties, shape is the most controversial. In previous discrete fracture network models, discontinuities have been considered to be limited or unlimited planes, but in reality curved discontinuities are also observed. Based on previous research, the planar assumption in rocks containing curved discontinuities leads to considerable errors in subsequent analyses. Curved discontinuities and reasons for their formation have not yet been specifically classified. However, it is obvious that there are several reasons for the creation of these types of discontinuities. Folding is the most common factor responsible for the generation of curved discontinuities. In this paper, a practical 3D geometric method is proposed to model folded rock layers. The method relies on Fourier analysis to model the folded layer and generates suitable input data for subsequent mechanical analysis via a purposely developed MATLAB script named RocFold. The applicability of the proposed model and script is tested by using an example of a typical folded structure in the Anjire mine, Iran.