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<p>In underground engineering projects such as subway systems, tunnel networks, and mining operations, the interaction between rock creep behavior and thermal stability poses significant challenges to structural integrity and construction efficiency. This study comprehensively investigates the creep behavior of sandstone at elevated temperatures (300–800&#xa0;°C) by integrating macroscopic mechanical testing with microscopic analysis. By comparing two loading methods—staged loading and step loading—the research demonstrates that, under identical temperature and stress conditions, staged loading results in significantly greater creep strains than step loading, with a maximum difference of 0.416% observed at 500&#xa0;°C. Both loading methods exhibit temperature-dependent increases in the transient and steady-state creep phases, consistent with progressive microstructural degradation. Detailed microstructural examinations reveal thermally activated processes such as intergranular dehydration and the development of fracture networks, which become increasingly pronounced as temperatures approach 800&#xa0;°C. A modified Nishihara constitutive model incorporating thermal-damage factors is developed to characterize creep behavior under both loading modes. Furthermore, the study quantitatively analyzes the thermal evolution of the Nishihara model parameters under these two distinct creep conditions.</p>

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Experimental Study and Analysis of Creep of High Temperature Sandstone Under Different Loading Modes

  • 期刊论文

  • 发表日期：

    2025年12月26日

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  • Mingze Qin,
  • Yifan Zhang,
  • Wenjie Zhang,
  • Yue Su,
  • Zhongyu Wang,
  • Nan Qin,
  • Kun Liu,
  • Songmei Li

摘要

In underground engineering projects such as subway systems, tunnel networks, and mining operations, the interaction between rock creep behavior and thermal stability poses significant challenges to structural integrity and construction efficiency. This study comprehensively investigates the creep behavior of sandstone at elevated temperatures (300–800 °C) by integrating macroscopic mechanical testing with microscopic analysis. By comparing two loading methods—staged loading and step loading—the research demonstrates that, under identical temperature and stress conditions, staged loading results in significantly greater creep strains than step loading, with a maximum difference of 0.416% observed at 500 °C. Both loading methods exhibit temperature-dependent increases in the transient and steady-state creep phases, consistent with progressive microstructural degradation. Detailed microstructural examinations reveal thermally activated processes such as intergranular dehydration and the development of fracture networks, which become increasingly pronounced as temperatures approach 800 °C. A modified Nishihara constitutive model incorporating thermal-damage factors is developed to characterize creep behavior under both loading modes. Furthermore, the study quantitatively analyzes the thermal evolution of the Nishihara model parameters under these two distinct creep conditions.