FRACTAL CHARACTERISTICS OF ROCK DISCONTINUITIES

The discontinuities in a rock mass usually control its overall behavio r. Rock mass deformability, stability of underground excavations, and flow of fluid depend significantly on the intensity, the degree of int erconnection, and the characteristics of the fracture network present. We apply the theory of fractal geometry to describe the rock fracture network. Three parameters characterize the discontinuities visible in the exposed face of the investigated rock mass. The first parameter m easures the complexity of the network formed by the individual traces of the discontinuities. The intensity and the interconnectivity of the discontinuities are characterized by the fracture density and the blo ck density respectively. We use data from four faces of a copper mine in Arizona. All three parameters show fractal characteristics over the range investigated with coefficients of determination better than 0.9 9. The fractal structure of these parameters suggests that the rock fr acturing process may be a scale-independent phenomenon.