Fully Coupled Thermo-Hydro-Mechanical Modeling of Discontinuities in Porous Media Incorporating High Aspect Ratio Interface Elements

The process of evolving discontinuities (in the form of fractures, cracks or fissures) in porous media is a very complex problem and possesses several challenges. This research proposal aims to progress the current understanding in this area by developing a fully coupled thermo-hydromechanical (THM) approach. The discontinuity will be modeled by using the mesh fragmentation technique (MFT), which consists of introducing finite elements with high aspect ratio between the standard (bulk) elements of the mesh. This new methodology has been successfully employed in concrete structures and soils, but by only assuming the mechanical problem. In this dissertation, the mass and heat flows are also incorporated in the formulation by considering THM processes. The MFT has been implemented in the in house CODE_BRIGHT finite element program, which was originally developed to solve coupled THM problems in continuous porous media. In this context, numerical simulations were performed in order to achieve a better understanding of discontinuities under complex conditions, mimicking desiccation tests in soils and energy production in rock reservoirs. The results have shown that the technique is very promising to model the formation and propagation of discontinuities in geo-engineering problems