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<p>The stability of grouted rock masses under high temperatures is critical for the safe operation of tunnels following post-fire rehabilitation. To investigate the progressive failure behavior of grouted rock masses under high-temperature conditions, uniaxial compression tests were conducted on fracture-grouted sandstone specimens with fracture angles of 30°, 45°, and 60° after thermally treating them at temperatures ranging from 25 to 800 ℃. Acoustic emission (AE) and digital image correlation (DIC) were used synchronously to capture the spatiotemporal evolution of internal microcracks and surface failure evolution during loading. The results showed that increasing the temperature increased the density of the thermal cracks, which prolonged the compaction stage owing to the extended crack-closure process. Meanwhile, the peak stress decreased, whereas the peak strain increased, corresponding to a reduced peak AE release intensity and higher DIC-measured strain values. The strain localization zones propagated along tensile wing crack paths at ambient temperature but progressively merged with far-field strain localization zones at high temperatures, leading to a transition in the failure mode from tensile-dominated failure controlled by stress concentration to tensile–shear mixed failure controlled by a thermal crack network. Correspondingly, the AF–RA distribution gradually shifted toward the shear region, with an increasing proportion of shear-type AE events. Furthermore, an improved cohesive fracture model incorporating interfacial thermal damage and mixed-mode failure was developed by establishing a nonlinear relationship between intergranular contact parameters and interfacial fracture displacement and by introducing a thermal damage factor to modify the inelastic degradation path of contact yielding. Numerical simulations integrating the proposed model with the grain-based method successfully reproduced the damage mechanism among sandstone mineral grains and along the grout–rock interfaces under high-temperature conditions. These findings provide insights into the instability mechanisms of grouted rock masses at high temperatures.</p>

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Progressive Failure Behavior of Fracture-Grouted Sandstone After High-Temperature Treatment During Uniaxial Loading: Insights from AE-DIC Experiments and Grain-Based Cohesive Modeling

  • 期刊论文

  • 发表日期：

    2026年7月24日

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  • Haoyang Zhang,
  • Annan Jiang,
  • Fu Zheng,
  • Linlin Liu,
  • Minghao Hao

摘要

The stability of grouted rock masses under high temperatures is critical for the safe operation of tunnels following post-fire rehabilitation. To investigate the progressive failure behavior of grouted rock masses under high-temperature conditions, uniaxial compression tests were conducted on fracture-grouted sandstone specimens with fracture angles of 30°, 45°, and 60° after thermally treating them at temperatures ranging from 25 to 800 ℃. Acoustic emission (AE) and digital image correlation (DIC) were used synchronously to capture the spatiotemporal evolution of internal microcracks and surface failure evolution during loading. The results showed that increasing the temperature increased the density of the thermal cracks, which prolonged the compaction stage owing to the extended crack-closure process. Meanwhile, the peak stress decreased, whereas the peak strain increased, corresponding to a reduced peak AE release intensity and higher DIC-measured strain values. The strain localization zones propagated along tensile wing crack paths at ambient temperature but progressively merged with far-field strain localization zones at high temperatures, leading to a transition in the failure mode from tensile-dominated failure controlled by stress concentration to tensile–shear mixed failure controlled by a thermal crack network. Correspondingly, the AF–RA distribution gradually shifted toward the shear region, with an increasing proportion of shear-type AE events. Furthermore, an improved cohesive fracture model incorporating interfacial thermal damage and mixed-mode failure was developed by establishing a nonlinear relationship between intergranular contact parameters and interfacial fracture displacement and by introducing a thermal damage factor to modify the inelastic degradation path of contact yielding. Numerical simulations integrating the proposed model with the grain-based method successfully reproduced the damage mechanism among sandstone mineral grains and along the grout–rock interfaces under high-temperature conditions. These findings provide insights into the instability mechanisms of grouted rock masses at high temperatures.