Effect of the Single Central Pre‐Existing Fissure With Different Angles on Rockburst Proneness of Granite: Mechanistic Insights via Three‐Dimensional Grain‐Based Modeling

ABSTRACT To explore the influence of pre‐existing fissure angles on the proneness of granite rockburst, this paper constructs an analysis approach using a three‐dimensional grain‐based model (3D‐GBM) that utilizes the particle flow method. In the verification of the numerical model, the stress‐strain curves and failure modes in the simulation of standard uniaxial compression tests exhibit a high level of congruence with laboratory test outcomes. Relative errors in uniaxial compressive strength and elastic modulus are both below 10%. The numerical simulation tests of one‐cycle loading‐unloading compression (OCLUC) show that the discrepancy between the peak strength obtained from the OCLUC test and that from the standard uniaxial compression test for each type specimen at varying unloading stress levels α does not exceed 5%. The unloading stress level α has little effect on the distribution of microcracks, but only affects the fracture degree. Meanwhile, different specimens exhibit distinct characteristics in terms of the force chain network. Pre‐existing fissures guide particle movement, and the unloading stress level regulates the intensity of such directional concentration. According to the numerical simulation, in conjunction with the standard of peak‐strength strain energy storage index W et p , it is calculated that all five types of granite specimens have high rockburst proneness. The intact N‐type specimen has the largest W et p = 6.0748, while the specimen with 60° pre‐existing fissure has the smallest W et p = 5.0429.