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<p>Flaw geometry fundamentally governs fracture dynamics in rock, yet the mechanistic distinction between blunt and sharp defects remains poorly understood. This study integrates Brazilian disc experiments and numerical simulations to investigate how circular holes (simulating pores) and chevron notches (simulating fissures) control crack evolution in sandstone. Results show that geometry dictates fracture behavior not by altering macroscopic failure mode, but by locally manipulating stress fields Circular holes act as passive stress perturbators, promoting diffuse branching without altering primary fracture paths. In contrast, V-shaped notches serve as active fracture nuclei, generating near-singular stress intensification that drives crack initiation directly from the flaw. This establishes a clear hierarchy of weakening, with peak load reductions following a progressive sequence from intact to double-hole to chevron-notched specimens. Acoustic emission signals reveal phase-specific fingerprints: low-frequency (~ 100&#xa0;kHz) signals mark shear initiation at loading ends; high-frequency bimodal signals (200–400&#xa0;kHz) indicate tensile coalescence at centers. These findings demonstrate that sharp discontinuities pose fundamentally greater threats than blunt cavities, with implications for rock mass stability and hazard mitigation in mining, civil, and petroleum engineering.</p>

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Flaw geometry controls rock fracture: perturbation by blunt pores versus nucleation by sharp fissures

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年5月15日

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  • Zhendong Cui,
  • Weige Han,
  • Kai Si,
  • Xiao Li

摘要

Flaw geometry fundamentally governs fracture dynamics in rock, yet the mechanistic distinction between blunt and sharp defects remains poorly understood. This study integrates Brazilian disc experiments and numerical simulations to investigate how circular holes (simulating pores) and chevron notches (simulating fissures) control crack evolution in sandstone. Results show that geometry dictates fracture behavior not by altering macroscopic failure mode, but by locally manipulating stress fields Circular holes act as passive stress perturbators, promoting diffuse branching without altering primary fracture paths. In contrast, V-shaped notches serve as active fracture nuclei, generating near-singular stress intensification that drives crack initiation directly from the flaw. This establishes a clear hierarchy of weakening, with peak load reductions following a progressive sequence from intact to double-hole to chevron-notched specimens. Acoustic emission signals reveal phase-specific fingerprints: low-frequency (~ 100 kHz) signals mark shear initiation at loading ends; high-frequency bimodal signals (200–400 kHz) indicate tensile coalescence at centers. These findings demonstrate that sharp discontinuities pose fundamentally greater threats than blunt cavities, with implications for rock mass stability and hazard mitigation in mining, civil, and petroleum engineering.