Characterizing the influence of stress-induced microcracks on the laboratory strength and fracture development in brittle rocks using a finite-discrete element method-micro discrete fracture network FDEM-μDFN approach

An Extended Grain‐Based Model Accounting for Microstructures in Rock Deformation

“…At the laboratory scale, a similar concept has been introduced to establish a micromodel (Hamdi et al, ; Lisjak, Tatone, et al, ) for characterizing initial microcracks. Unlike grain boundaries that can be identified by the chromatic and mineralogical characteristics, deterministic characterization of initial microcracks is practically unrealistic.…”

“…In line with the generation of the microdiscrete fracture network (μDFN) model (Hamdi et al, ), thin sections are analyzed for obtaining the two‐dimensional microcrack statistics. Assuming that natural microcracks formed within the same mineral type of a rock specimen will have similar properties such as the preferential orientations, microcracks distributed within different mineral types are identified separately.…”

“…The microcrack properties used to generate a DFN model include length, orientation, and density (P21). Microcrack density (P21) is defined as the total length of microcracks per unit area (Hamdi et al, ). The total microcrack length can be calculated simply by summating the lengths of all the microcracks traced within each type of mineral.…”

“…Although computational demand tends to hinder its large‐scale applications, the DEM approach is favorable for its versatility to capture the geometric complexity of rocks at the grain scale. With the hybrid finite‐discrete element methods, preexisting microcracks are incorporated by either initial characterization (Hamdi et al, ) or reproducing the end effect (Cai, ; Lisjak, Grasselli, & Vietor, ; Lisjak, Tatone, et al, ; Mahabadi, ). Zhang and Wong () systematically assessed the capabilities and limitations of a number of numerical methods for simulating rock deformation and failure from a microstructural perspective.…”

“…The key role of initial microcracks in dominating the fracturing process has been well recognized as stress concentrators that can lead to local failures (Lajtai, ). In the context of numerical simulations, most studies consider only grain boundary microcracks, but less effort has been placed on the characterization of intragranular and transgranular cracks (Hamdi et al, ; Hofmann, Babadagli, Yoon, et al, ). For accurate representation of grain‐scale heterogeneity and discontinuity, microcomputerized tomography scanning technology and thin section images are employed to obtain microscale phase distribution and microcracks, respectively, which are then directly mapped to a combined finite‐discrete element model to simulate the tensile behavior of crystalline rocks (Mahabadi et al, ).…”