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<p>Multiscale degradation and early warning studies of weathered rock in cold regions are limited. This study investigates the evolution of mineral composition, pore structure, and physico-mechanical properties of weathered granite using mineralogical analysis, low-field nuclear magnetic resonance (NMR), mechanical testing, and acoustic emission (AE) monitoring. A multiscale degradation correlation mechanism linking microcracks, mesoscopic pores, and macroscopic properties was established based on Pearson correlation analysis. Based on critical slowing down (CSD) theory, the early warning characteristics of AE parameters were analyzed, revealing a correlation between recovery rate (<i>λ</i>) and brittleness index (BI). Results indicate that weathering alters the mineral composition and pore structure of granite, resulting in decreased mass, volume, P-wave, uniaxial compressive strength, and elastic modulus, while both permeability coefficient and maximum strain increase. Porosity increased from 0.13 to 4.01%, with the proportion of macropores rising from 23.19 to 36.62% at the completely weathered stage. The increased fractal dimension indicates greater pore complexity. Peak AE energy decreased from 65,535–2838&#xa0;mV·ms, indicating reduced rupture strength. RA–AF analysis revealed that tensile crack proportion increases with weathering. The CSD phenomenon is observed in AE energy, rise time, counts, and RA values, with the choice of window length and lag length influencing the reliability of the early warning signals. A dual-parameter early warning model combining variance and autocorrelation coefficient is recommended to balance reliability and lead time. The BI and <i>λ</i> are positively correlated, and reductions in both lead to a decrease in variance early warning time ratio from 97.35 to 68.47%.</p>

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Study on the Multiscale Degradation Correlation Mechanism and Critical Slowing Down Characteristics of Weathered Granite in Cold Regions

  • 期刊论文

  • 发表日期：

    2025年9月3日

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  • Hexing Zhang,
  • Qiang Xie,
  • Kunpeng Lu,
  • Weichen Sun,
  • Zhengnan Tu,
  • Yucheng Chen

摘要

Multiscale degradation and early warning studies of weathered rock in cold regions are limited. This study investigates the evolution of mineral composition, pore structure, and physico-mechanical properties of weathered granite using mineralogical analysis, low-field nuclear magnetic resonance (NMR), mechanical testing, and acoustic emission (AE) monitoring. A multiscale degradation correlation mechanism linking microcracks, mesoscopic pores, and macroscopic properties was established based on Pearson correlation analysis. Based on critical slowing down (CSD) theory, the early warning characteristics of AE parameters were analyzed, revealing a correlation between recovery rate (λ) and brittleness index (BI). Results indicate that weathering alters the mineral composition and pore structure of granite, resulting in decreased mass, volume, P-wave, uniaxial compressive strength, and elastic modulus, while both permeability coefficient and maximum strain increase. Porosity increased from 0.13 to 4.01%, with the proportion of macropores rising from 23.19 to 36.62% at the completely weathered stage. The increased fractal dimension indicates greater pore complexity. Peak AE energy decreased from 65,535–2838 mV·ms, indicating reduced rupture strength. RA–AF analysis revealed that tensile crack proportion increases with weathering. The CSD phenomenon is observed in AE energy, rise time, counts, and RA values, with the choice of window length and lag length influencing the reliability of the early warning signals. A dual-parameter early warning model combining variance and autocorrelation coefficient is recommended to balance reliability and lead time. The BI and λ are positively correlated, and reductions in both lead to a decrease in variance early warning time ratio from 97.35 to 68.47%.