American Geophysical Union, California, United States Of America, 9 - 13 December 2019, pp.1-2
The purpose of this work is to investigate how strain localizes in hard rock, related to microcracking at different stages of direct tensile loading. A three-dimensional discrete element modeling approach (DEM) is used for the numerical analyses and a calibration process is conducted through Yade-open DEM code to reproduce the mechanical behaviors of Forsmark granite (in Sweden) as a typical example of hard rock. After ensuring that the numerical model represents the real rock material's mechanical responses, the origins of the damage process developing in hard rocks are explained with the calculation of the incremental strain fields as well as presenting the spatiotemporal distributions of tensile microcracks and displacement vectors in the numerical model.
The model predictions show that the microcrack initiation threshold (σci) is about 62.5% of the peak stress while the damage related to the diffuse microcracking propagates irrepressibly at 87.5% of the yielding point. After this level, the strain becomes to localize in specific areas into the model sample, leading a macro-fracture at the failure. The model results also suggest that at the early stages of the loading, the distributions of displacement vectors and microcracks can be correlated with the location of the forthcoming damage zone. This explicitly indicates the critical stress level at the pre-failure part of the stress-strain curve where the damage in the model sample cannot be prevented anymore.