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<p>The failure characteristics of high-temperature rocks are pivotal to safe and efficient operations in many underground rock engineering fields. To reveal the failure characteristics of sandstones, the paper aims to analyze mechanical properties, crack evolution, and failure modes after heat-treated sandstones under Brazilian splitting loads by coupling of internal failure hypocenters detected by acoustic emission (AE) with the surface deformation field obtained using‌ digital image correlation (DIC). X-ray computed tomography (CT) was used to identify the main factors affecting mechanical properties and failure characteristics. The results indicate that the evolution processes of failure hypocenters and the evolution of the horizontal strain field exhibit similarities but are not fully synchronized. The longitudinal wave velocity, tensile strength, tensile modulus, and deformation coefficient at 1000℃ are reduced by 45.82%, 74.21%, 71.53%, and 75% respectively, compared with those at 400℃. The sandstones exhibit a threshold temperature of 400&#xa0;°C. When the temperature is ≤ 400&#xa0;°C, the failure evolution involves‌ tensile failure initiating at the loading points and propagating toward the center. Above 400℃, the crack evolution path reverses, starting from the center of the sample and propagating toward the loading ends. CT results reveal that as temperatures increase, the pore-crack distribution has a more significant effect on the characteristics of splitting failure. For rock samples at 25 ℃ and those subjected to heat treatment at 200–600℃, cracks initiate and propagate from pore-cracks distributed along the loading direction. After treatment at 800–1000&#xa0;°C, the proportion of AE hypocenters originating from pore-cracks reaches as high as 99.35%.</p>

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The failure characteristics of heat-treated sandstone subjected to splitting loading and the pore-crack distribution effects

  • 期刊论文

  • 发表日期：

    2026年7月29日

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  • Tong Qi,
  • Jie Zhu,
  • Yubo Zhang,
  • Zhiyuan Cheng,
  • Yu Wu

摘要

The failure characteristics of high-temperature rocks are pivotal to safe and efficient operations in many underground rock engineering fields. To reveal the failure characteristics of sandstones, the paper aims to analyze mechanical properties, crack evolution, and failure modes after heat-treated sandstones under Brazilian splitting loads by coupling of internal failure hypocenters detected by acoustic emission (AE) with the surface deformation field obtained using‌ digital image correlation (DIC). X-ray computed tomography (CT) was used to identify the main factors affecting mechanical properties and failure characteristics. The results indicate that the evolution processes of failure hypocenters and the evolution of the horizontal strain field exhibit similarities but are not fully synchronized. The longitudinal wave velocity, tensile strength, tensile modulus, and deformation coefficient at 1000℃ are reduced by 45.82%, 74.21%, 71.53%, and 75% respectively, compared with those at 400℃. The sandstones exhibit a threshold temperature of 400 °C. When the temperature is ≤ 400 °C, the failure evolution involves‌ tensile failure initiating at the loading points and propagating toward the center. Above 400℃, the crack evolution path reverses, starting from the center of the sample and propagating toward the loading ends. CT results reveal that as temperatures increase, the pore-crack distribution has a more significant effect on the characteristics of splitting failure. For rock samples at 25 ℃ and those subjected to heat treatment at 200–600℃, cracks initiate and propagate from pore-cracks distributed along the loading direction. After treatment at 800–1000 °C, the proportion of AE hypocenters originating from pore-cracks reaches as high as 99.35%.