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<p>Thermo-mechanical coupling conditions exist in various engineering scenarios, such as deep coal mining, in-situ coal seam heat injection, underground gasification and liquefaction, and coal seam spontaneous combustion. To investigate the effects of temperature on the deformation, strength, failure characteristics, and damage mechanisms of coal, coal samples were heated to simulate the high-temperature environment in deep coal seams and subjected to uniaxial compression to replicate high-stress loads. The results indicate that the coal samples undergo four stages considering thermal damage under uniaxial compression: compaction, linear elasticity, plasticity, and post-peak failure. Elevated temperature promotes the development of the compaction stage and enhances the post-peak plastic deformation. The peak strength and elastic modulus decrease with increasing temperature and a high strength sensitivity to temperature. The crack closure strain is positively correlated with the temperature, while the crack closure stress is negatively correlated. The crack damage stress and strain exhibit a trend of initially increasing and decreasing with rising temperature. Temperature significantly affects the damage extension stage. As temperature increases, the failure mode transforms from shear failure to a combination of multiple types. High temperature also increases the fractal dimension of coal sample fragments and promotes acoustic emission (AE) events, resulting in more complex failure degrees and morphologies. At room temperature, AE events significantly increase during the plastic stage, while it gradually becomes active during the linear elastic stage after high-temperature treatment. The indirect AE parameters effectively characterize different crack types. An abnormal damage constitutive model was proposed to describe coal samples’ full deformation and failure process under thermo-mechanical coupling. Statistical parameters indicate that the proposed constitutive model matches the stress–strain curves well, outperforming conventional constitutive models.</p>

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Mechanical Properties and Thermo-mechanical Damage Constitutive Model of Coal Subjected to Thermal Treatments Under Uniaxial Compression

  • 期刊论文

  • 发表日期：

    2025年12月22日

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  • Zhuo Dong,
  • Guoxin Cheng,
  • Yingxian Lang,
  • Zhengzhao Liang,
  • Ruifu Yuan,
  • Yingying Shi

摘要

Thermo-mechanical coupling conditions exist in various engineering scenarios, such as deep coal mining, in-situ coal seam heat injection, underground gasification and liquefaction, and coal seam spontaneous combustion. To investigate the effects of temperature on the deformation, strength, failure characteristics, and damage mechanisms of coal, coal samples were heated to simulate the high-temperature environment in deep coal seams and subjected to uniaxial compression to replicate high-stress loads. The results indicate that the coal samples undergo four stages considering thermal damage under uniaxial compression: compaction, linear elasticity, plasticity, and post-peak failure. Elevated temperature promotes the development of the compaction stage and enhances the post-peak plastic deformation. The peak strength and elastic modulus decrease with increasing temperature and a high strength sensitivity to temperature. The crack closure strain is positively correlated with the temperature, while the crack closure stress is negatively correlated. The crack damage stress and strain exhibit a trend of initially increasing and decreasing with rising temperature. Temperature significantly affects the damage extension stage. As temperature increases, the failure mode transforms from shear failure to a combination of multiple types. High temperature also increases the fractal dimension of coal sample fragments and promotes acoustic emission (AE) events, resulting in more complex failure degrees and morphologies. At room temperature, AE events significantly increase during the plastic stage, while it gradually becomes active during the linear elastic stage after high-temperature treatment. The indirect AE parameters effectively characterize different crack types. An abnormal damage constitutive model was proposed to describe coal samples’ full deformation and failure process under thermo-mechanical coupling. Statistical parameters indicate that the proposed constitutive model matches the stress–strain curves well, outperforming conventional constitutive models.