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<p>The dynamic tensile mechanical properties and damage evolution fracture mechanisms of roof rock media in goaf areas under high-temperature conditions are key to ensuring the safe and green extraction of coal resources above the goaf, especially in cases of coal spontaneous combustion or underground coal gasification. Based on the conclusions from dynamic direct tensile tests of coal–rock media under high-temperature environments, this study employs coupled continuum–discrete numerical methods to establish a separable Hopkinson tension bar system (SHTB) numerical model, a three-dimensional equivalent particle model (GBM) of the roof rock media specimens, and a thermal pipe model representing the thermal damage effects on the roof rock media. Research confirms that the simulation results accurately capture the dynamic direct tensile mechanical behavior of sandstone subjected to high-temperature damage. Under elevated temperatures, the response of coal-bearing sandstone exhibits distinct stage characteristics, as evidenced by the non-monotonic trend in which the slope of the linear relationship between strength and strain rate first increases and then decreases, along with a four-stage evolution pattern of impact tensile damage fracture. Throughout this process, the evolution of mesoscopic force chains serves as the underlying mechanism driving the changes in macroscopic mechanical behavior. In addition, impact velocity is identified as a key parameter influencing the energy dissipation characteristics of the material.</p>

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Tensile Mechanical Properties and Damage Evolution Fracture Mechanism of Overlying Strata in Goaf under Thermo-mechanical Dynamic Coupling Conditions

  • 期刊论文

  • 发表日期：

    2026年4月30日

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  • Kun Xu,
  • Yanlong Chen,
  • Ming Li,
  • Qian Yin,
  • Yafei Zhang,
  • Fuqiang Zhu,
  • Jishuo Deng

摘要

The dynamic tensile mechanical properties and damage evolution fracture mechanisms of roof rock media in goaf areas under high-temperature conditions are key to ensuring the safe and green extraction of coal resources above the goaf, especially in cases of coal spontaneous combustion or underground coal gasification. Based on the conclusions from dynamic direct tensile tests of coal–rock media under high-temperature environments, this study employs coupled continuum–discrete numerical methods to establish a separable Hopkinson tension bar system (SHTB) numerical model, a three-dimensional equivalent particle model (GBM) of the roof rock media specimens, and a thermal pipe model representing the thermal damage effects on the roof rock media. Research confirms that the simulation results accurately capture the dynamic direct tensile mechanical behavior of sandstone subjected to high-temperature damage. Under elevated temperatures, the response of coal-bearing sandstone exhibits distinct stage characteristics, as evidenced by the non-monotonic trend in which the slope of the linear relationship between strength and strain rate first increases and then decreases, along with a four-stage evolution pattern of impact tensile damage fracture. Throughout this process, the evolution of mesoscopic force chains serves as the underlying mechanism driving the changes in macroscopic mechanical behavior. In addition, impact velocity is identified as a key parameter influencing the energy dissipation characteristics of the material.