Abstract：A numerical model of three-dimensional discrete fracture networks for seepage in fractured rocks is presented. Fractures are modeled as circular or quadrangular disks with arbitrary size，orientation，location and transmissivity. A fracture network is characterized by the statistical distributions of these parameters. Based on this model，a code for predicting seepage in fractured rocks，FracFlow，is developed，which can estimate the statistical distribution of the appropriate geometric parameters through field measurements，generate statistically identical fracture network，and compute the flow responses of this fracture network. The program can also use site-specific geometric data to generate fracture network. Boundary element method is used to discretize the fracture network and solve the problem of seepage. In the first part of this paper，only the detailed process of the generation of three-dimensional stochastic fracture networks using field data is introduced. At last two samples are given for the calibration of this program.
