Dynamic fracture mechanism of granite with different shape holes under high strain rates based on HFDEM

• Granite with long elliptical holes exhibits the highest dynamic strength, while short elliptical holes yield the lowest, under similar strain rates. • The superior strength of long elliptical holes is attributed to weak axial stress concentration and dispersed transverse stress. • Failure of granite with holes is predominantly tensile-shear mixed fracture, with minimal pure type II cracks. • The transverse span of the chamber is the primary factor controlling the extent of the fracture zone.