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Publication 24-CNA-020
Phase-Field Modeling of Fracture under Compression and Confinement in Anisotropic Geomaterials Maryam Hakimzadeh Carlos Mora-Corral Noel J. Walkington Giuseppe Buscarnera Kaushik Dayal Building on a recently-developed phase-field model that accounts for compressive traction across the crack face, this paper extends the model to the setting of anisotropic fracture. The key features of the model include: (1) a homogenized anisotropic elastic response and strongly-anisotropic model for the work to fracture; (2) an effective damage response that accounts consistently for compressive traction across the crack face, that is derived from the anisotropic elastic response; (3) a regularized crack normal field that overcomes the shortcomings of the isotropic setting, and enables the correct crack response, both across and transverse to the crack face. To test the model, we first compare the predictions to phase-field fracture evolution calculations in a fully resolved layered specimen with spatial inhomogeneity, and show that it captures the overall patterns of crack growth. We then apply the model to previously-reported experimental observations of fracture evolution in laboratory specimens of shales under compression with confinement, and find that it predicts well the observed crack patterns in a broad range of loading conditions. We further apply the model to predict the growth of wing cracks under compression and confinement. Prior approaches to simulate wing cracks have treated the initial cracks as an external boundary, which makes them difficult to apply to general settings. Here, the effective crack response model enables us to treat the initial crack simply as a non-singular damaged zone within the computational domain, thereby allowing for easy and general computations. Get the paper in its entirety as 24-CNA-020.pdf |