Numerical modeling of self-sealing process in cracked clayey rocks by using Enhanced Finite Element Method (E-FEM)

In the context of the geological disposal of radioactive waste, the self-sealing of excavation-induced cracks in host rock is a key issue to investigate. In this study, we develop a novel numerical model based on Enhanced Finite Element Method (E-FEM). By incorporating strong displacement discontinuities across cracks, the evolution of crack aperture can be explicitly quantified. Our model contains several new features: introduction of pre-existing cracks and their subsequent progressive closure, consideration of hydro-mechanical coupling in partially saturated porous media, swelling deformation of clayey rocks due to water saturation. Moreover, permeability change is directly calculated from varying crack aperture through cubic-law. The proposed model is applied to modeling crack closure and self-sealing in Callovo-Oxfordian (COx) claystone which is selected as the host formation for geological disposal project in France. Numerical simulations of representative laboratory tests are performed, and the results are compared with experimental data. The proposed model is able to reproduce the main coupled mechanisms involved in the self-sealing process in cracked clayey rocks.