ABSTRACT
Coupled hydro–mechanical (HM) processes in fractured porous media govern the performance and safety of several subsurface engineering applications, where pressure-driven changes in stress and permeability can control injectivity, leakage pathways, and fault reactivation potential. This thesis develops a robust and versatile finite element formulation for transient HM problems in the presence of pre-existing strong discontinuities that remains practical for integration into standard finite element workflows. The proposed approach is formulated within the Embedded Finite Element Method (E-FEM) and grounded on the Strong Discontinuity Approach (SDA), enabling an implicit representation of fractures and faults while circumventing mesh conformity constraints. A unified description is introduced to model discontinuities acting either as preferential flow paths or as hydraulic barriers, capturing the longitudinal flow along the discontinuity and the transversal exchange with the porous matrix in steady-state and transient settings. The formulation is systematically verified against discrete fracture models with interface elements and applied to benchmark problems representative of fractured-reservoir conditions, including a coupled fault reactivation scenario. In addition, the thesis investigates the occurrence of spurious oscillations in cohesive traction fields along embedded discontinuities and demonstrates that the choice of an SDA-based embedded formulation can markedly improve traction smoothness. These improvements strengthen the use of E-FEM for HM assessments involving pre-existing fractures and faults.
PhD Advisors:
PHD CANDIDATE
Danilo Cavalcanti holds a bachelor’s degree in Civil Engineering from the Federal University of Goiás (2020), a Master’s degree in Civil Engineering (Structures) from the Federal University of Goiás (2022), and is a PhD candidate from both Pontifical Catholic University of Rio de Janeiro and Universitat Politecnica de Catalunya (UPC). He had the opportunity to work at the Multiphysics Modeling and Simulation group at Tecgraf Institute/PUC-Rio as a PhD student and since March 2023, he has worked as a Research Engineer at CIMNE. His areas of research and interest are: computational geomechanics and finite element formulations.