Numerical Analysis of Tensile Behavior in Heterogeneous Rock Using a Grain-Based Discontinuous Deformation Analysis

To meet the increasing demands of construction, rock engineering has become a hot topic in modern engineering. Notably, the tensile failure of rocks still significantly affects the safety of rock engineering. Discontinuous deformation analysis (DDA), an implicit discrete-element method, is well-suited for modeling the deformation behavior of blocky rock masses. To investigate the role of mineral grain characteristics in the initiation, propagation, and coalescence of microcracks during tensile loading, in this study, a statistically representative Voronoi grain-based model was developed within the DDA framework (GB-DDA). After the model was calibrated using mesoscopic parameters, the GB-DDA approach demonstrated strong agreement with experimental results for Barre granite under both tensile and compressive conditions, enabling a detailed quantitative analysis of intragranular and intergranular damage evolution. To further evaluate the effects of mesoscopic heterogeneity on tensile behavior, some GB-DDA numerical models were constructed by varying the average grain size, grain roundness, and mineral content. Under the quasi-static Brazilian splitting condition, the simulations revealed a consistent order in crack types, with intergranular tensile cracks occurring most frequently, followed by intragranular tensile cracks, intergranular shear cracks, and intragranular shear cracks. Among them, the failure process was overwhelmingly dominated by tensile cracking. The results showed that an increase in average grain size or biotite content and a reduction in grain roundness led to a notable decrease in Brazilian tensile strength. Larger grain size and lower grain roundness promoted earlier crack initiation and resulted in a more uniform angular distribution of tensile cracks. In contrast, variations in biotite content had little effect on the timing of initial cracks or orientation of tensile cracks. Additionally, the occurrence of intergranular cracks was promoted by increases in average grain size, grain roundness, and biotite content.