Embedding Discrete, Irregular Fracture Zone Networks in Three-Dimensional Groundwater Flow Models

In fractured crystalline rock settings, the presence and distribution of fracture zones in the geosphere will strongly influence groundwater system behaviour. Dual continuum computational models that include both porous media and discrete fracture zones are valuable tools in assessing groundwater flow and pathways in fractured rock systems. A methodology and algorithm are presented to incorporate a discrete, complex and irregular fracture zone network, represented as a triangulated two-dimensional mesh, within an orthogonal three-dimensional finite-element mesh. For this study, numerical groundwater models were used as a means to assemble, integrate and illustrate the role of geosphere parameters and properties. The numerical groundwater modelling was performed using HydroGeoSphere. A discrete fracture zone network model, generated using MoFrac and delineated from surface features, was superimposed onto a three-dimensional mesh. The MoFrac code enables the generation of geostatistically and structurally possible 3D fracture network models at the tunnel, site and regional scale.