Numerical Insights Into the Dynamic Tensile Fracture Propagation Mechanism of Rocks

ABSTRACT The notched semi‐circular bend (NSCB) specimen incorporating the split Hopkinson pressure bar (SHPB) is the only suggested dynamic mode I fracture testing method of rocks by the International Society for Rock Mechanics and Rock Engineering (ISRM). Constrained by current experimental techniques, the instantaneous fracture propagation details have yet to be fully elucidated. In this work, we re‐evaluate the dynamic transient propagation fracture properties of the NSCB specimen by discrete element method (DEM). Numerical results show that the complete crack propagating process can be well described by the logistic model. The moment tensor (MT) analysis results indicate that the tensile fracture mechanism dominates the whole fracture process. Detailed energy analysis shows that previous averaged propagation fracture toughness may be overestimated. The fracture propagation toughness is affected by both loading rate and crack velocity. These new insights provide significant implications for disaster prevention in rock engineering.