Theoretical and computational investigation of the fracturing behavior of anisotropic geomaterials

The fracturing process in geomaterials is studied to characterize a potential host rock for radioactive waste, such as the kaolinite-rich Opalinus Clay formation. Because of its sedimentary genesis, this rock can be considered as a transversely isotropic geomaterial. A semi-circular bending test is here modeled based on the eXtended Finite Element Method (XFEM), to check for the formation and propagation of cracks in the rock, with a particular focus on the effect of notch dimensions and scale effects on the fracturing response of the specimen in terms of peak load. Starting with the XFEM-based results, a novel analytical formulation is also proposed to approximate the response of the material in terms of load-crack mouth opening displacement. The proposed formulation is also capable to provide a reliable estimate of the peak value and time history response, compared to some experimental predictions from literature, starting from a predefined value of initial notch depth, which could represent a useful theoretical tool for design purposes.

Automated summary

This study investigates the fracturing process in geomaterials for characterizing a potential host rock for radioactive waste storage. A semi-circular bending test is modeled using the eXtended Finite Element Method (XFEM) to examine the formation and propagation of cracks in the rock. The study focuses on the effects of notch dimensions and scale on the fracturing response and proposes an analytical formulation for approximating the material's response in terms of load-crack mouth opening displacement.