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<p>The long-term stability of concrete linings is compromised by significant ground stress-induced creep and fire-related thermal degradation. This study investigated the damage evolution mechanism and creep characteristics of tunnel lining concrete at various temperatures. The mechanical characteristics of concrete deteriorated with the rising temperature and increasing constant temperature time, except for a strength rebound to 51.32&#xa0;MPa at 200&#xa0;°C and 60&#xa0;min. A predictive formula was established for the compressive strength of concrete after high temperatures based on the heating temperature, constant temperature time and ultrasonic velocity. In microstructure analysis, the porosity, average pore diameter, and roundness in concrete decreased and then increased as the temperature rose, with 200&#xa0;°C serving as the transition point, and the correlation between the average pore diameter and compressive strength was the strongest (the relation coefficient = 0.90). The axial and circumferential creep initially decreased and then increased, a trend that corresponded to the variation in residual compressive strength, and the effect of temperature on the axial creep rate was greater than that caused by stress. By introducing the thermal damage factor <i>D</i>, a nonlinear viscoelastic damage creep constitutive model was developed to characterize creep characteristics under high temperatures.</p>

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Damage and Creep Response of Tunnel Lining Concrete at Elevated Temperatures

  • 期刊论文

  • 发表日期：

    2026年1月6日

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  • Linlin Yao,
  • Linlin Gu,
  • Zhen Wang,
  • Zhiquan Huang,
  • Fei Gao

摘要

The long-term stability of concrete linings is compromised by significant ground stress-induced creep and fire-related thermal degradation. This study investigated the damage evolution mechanism and creep characteristics of tunnel lining concrete at various temperatures. The mechanical characteristics of concrete deteriorated with the rising temperature and increasing constant temperature time, except for a strength rebound to 51.32 MPa at 200 °C and 60 min. A predictive formula was established for the compressive strength of concrete after high temperatures based on the heating temperature, constant temperature time and ultrasonic velocity. In microstructure analysis, the porosity, average pore diameter, and roundness in concrete decreased and then increased as the temperature rose, with 200 °C serving as the transition point, and the correlation between the average pore diameter and compressive strength was the strongest (the relation coefficient = 0.90). The axial and circumferential creep initially decreased and then increased, a trend that corresponded to the variation in residual compressive strength, and the effect of temperature on the axial creep rate was greater than that caused by stress. By introducing the thermal damage factor D, a nonlinear viscoelastic damage creep constitutive model was developed to characterize creep characteristics under high temperatures.