Computational framework for analysis of contact-induced damage in brittle rocks

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This paper presents a numerical approach for predicting damage in rock materials caused by contact loading. The rock material is modelled using a constitutive description that combines pressure dependent plasticity, for capturing shear deformation under high confining pressure, with an anisotropic damage model for capturing mode I cracking in tension. Material parameters for the model are taken from a recently performed investigation on a granite material. The model has been used to simulate two types of contact loading experiments from the literature, cyclic loading and monotonic loading up to fracture. In order to achieve accurate predictions, the model has been extended to account for small loaded volumes which occur at contact loading. The results show that the main damage mechanism at cyclic loading is crack propagation due to Hertzian stresses whereas in the monotonic experiments sub-surface cracks could initiate. All features measured in the contact loading experiments are captured by the model and hence, the modelling framework is judged to be able to capture contact damage if real stone geometries are studied in FEM.