Modelling flow and solute transport in fractured porous media

A BEM numerical model is presented for the flow and solute transport in fractured porous media, which is based on the dual reciprocity method - multi domain scheme (DRM-MD). The model solves the 3D flow equation based on the Darcy law in the coupled system of porous media, fracture network and fracture intersections. Unlike the discrete fracture models, which for simplicity use Fick's law in the porous media, the present model solves the complete 3D advection-dispersion equation with reaction, which is then coupled with the other two models, the fracture network and the fracture intersections. In this work the developed model is used for long-term risk assessment of hazardous waste disposal in underground abandoned mines. The following sections describe three different models: the continuum model (313), the discrete-fracture model (2D) and the fracture intersection/pipe model (ID). The three models are integrated into a single model/simulation tool, which accounst for flow and transport through a system consisting of porous matrix, fractures and fracture intersections. The continuum, the fracture and the pipe models are tested and their performance verified using analytical solutions. This is done separately for each model, before the integration, and for the complete model after the three models are integrated. The results show that the integrated simulation tool has sufficient capability for modelling geometries and processes of complexity that are encountered in a real-world mine repositories.