Numerical study of critical behaviour of deformation and permeability of fractured rock masses

Abstract

The connectivity of fractures in rock masses is determined using a numerical simulation method. There is a continuous fracture cluster throughout a fractured rock mass if fracture density ( d) is at or above a threshold fracture density d c , Fractal dimension ( D f ) is used to describe the connectivity and compactness of the largest fracture clusters. D f increases with increasing fracture density. Percolation theory is used to determine the universal law, D f = A f ( d− d c ) f, which describes the critical behaviour of connectivity of fractures in rock masses. The results from numerical modeling show that the deformability of fractured rock masses increases greatly with increasing fracture density (i.e., fractal dimension), and the critical behaviour of deformability can be described by B s = A( d− d f ) s. Also, the overall permeability of a fractured rock mass occurs at or above a critical fracture density ( d c ) and increases with increasing fracture density. The critical behaviour of permeability can be described by q = A p ( d− d c ) p. The critical behaviour of connectivity and permeability of naturally fractured rock masses is examined using the universal forms.