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

Abstract

To elucidate the influence of confining pressure on microcrack evolution and macroscopic failure mechanisms in granite, a multi-perspective approach was adopted. This approach combined triaxial compression tests, acoustic emission (AE) monitoring, and PFC simulations. The results show that: 1) Confining pressure exhibits a pronounced linear correlation with both yield strength and compressive strength. The enhancement of confining pressure significantly improves the deformability of granite and promotes a progressive shift in failure mechanism from brittle rupture to ductile deformation; 2) Increasing confining pressure elevates the stress threshold for microcrack initiation and suppresses crack propagation. As a result, the proportion of shear cracks increases (based on AE analysis) from 18.71% to 61.2%, marking a transition in the dominant failure mode from tensile to shear; 3) Confining pressure facilitates the development of grain boundary shear cracks (GBSCs), establishing the primary damage pathways. In addition, local stress concentrations under high confinement conditions trigger intragranular cracking. This highlights the regulatory effect of confining pressure on microcrack evolution.

Keywords

granite / confining pressure / rock mechanics / failure mechanisms / acoustic emission / numerical simulation

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