Abstract：The realistic characterization of rock heterogeneity has been a long-standing problem of great practical interest. The heterogeneity of the fractured rock masses can be described by statistical random sampling in most numerical simulations. In this study，a digital image based(DIB) numerical method is proposed for the two-dimensional transient seepage analysis of the fractured rock masses by actually taking the spatial distribution of main fractures，minor fractures and intact rock into account. The digital image processing technique is developed to identify and classify the main structures(i.e. fractures，intact rocks) in the fractured rock masses and their intrinsic permeabilities are specified to these main structures. Then the characterized permeabilities of these structures are directly imported into newly developed three-dimensional simulator SCMR，a FEMLAB-based simulator of coupled multiphysics in rocks，to evaluate the effect of heterogeneity on the transient fluid flow in the fractured rock masses. The digital image based numerical results of transient fluid flow show that the digital image-based technique is capable to characterize the heterogeneity and the fracture structures of fractured rock masses. The digital image based technique is more advantageous than the statistical method in characterizing the rock heterogeneity and provides a new approach to obtain the realistic results.
