Mechanism of confining pressure-induced failure mode transition in granite: Implications from acoustic emission and numerical simulation

• Confining pressure linearly enhances yield and compressive strength, improving granite deformability and shifting failure from brittle to ductile. • Higher confining pressure raises microcrack initiation stress threshold and suppresses crack propagation, increasing shear crack proportion from 18.71% to 61.2%. • Confining pressure promotes grain boundary shear cracks (GBSCs) as primary damage pathways, with local stress concentrations inducing intragranular cracking. • Multi-perspective approach (triaxial tests, AE monitoring, PFC simulations) provides comprehensive understanding of microcrack evolution and failure mechanisms in granite.