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<p>To investigate the effect of freeze-thaw cycles on the fracture characteristics of jointed rock, laboratory studies were conducted using Bluish-Gray Sandstone specimens against the backdrop of frozen shaft wall excavation projects. Different freeze-thaw cycles were carried out on semi-circular specimens with 30° prefabricated cracks. Three-point bending tests were conducted using an MTS testing system. Highspeed camera and digital image correlation techniques were employed to analyze the evolution patterns within the fracture propagation zone (<i>FPZ</i>). Results indicate: Freeze-thaw cycles significantly degrade sandstone’s mechanical properties, with peak load (<i>P</i><sub><i>max</i></sub>) and Type I, Type II, and effective fracture toughness (<i>K</i><sub><i>IC</i></sub>, <i>K</i><sub><i>IIC</i></sub>, <i>K</i><sub><i>eff</i></sub>) progressively decreasing with increasing freeze-thaw cycles. Freeze-thaw cycles accelerated the propagation of microcracks within the rock specimens, leading to a gradual weakening of the peak characteristics in the fracture process zone. At high freeze-thaw cycles, the rate of decline slowed, indicating a transition in the rock failure mode from brittle fracture to ductile failure. The research results provide experimental data support for the safety design and stability evaluation of deep-frozen wellbore engineering.</p>

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Research on Fracture Characteristics and Crack Propagation Patterns of Freeze-Thaw Damaged Rock Under Loading

  • 期刊论文

  • 发表日期：

    2026年2月14日

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  • Ding Ma,
  • Mei-lu Yu,
  • Lin-kai He,
  • Zhong-wen Wang,
  • Zi-yi Yang,
  • Gen-shui Wu

摘要

To investigate the effect of freeze-thaw cycles on the fracture characteristics of jointed rock, laboratory studies were conducted using Bluish-Gray Sandstone specimens against the backdrop of frozen shaft wall excavation projects. Different freeze-thaw cycles were carried out on semi-circular specimens with 30° prefabricated cracks. Three-point bending tests were conducted using an MTS testing system. Highspeed camera and digital image correlation techniques were employed to analyze the evolution patterns within the fracture propagation zone (FPZ). Results indicate: Freeze-thaw cycles significantly degrade sandstone’s mechanical properties, with peak load (Pmax) and Type I, Type II, and effective fracture toughness (KIC, KIIC, Keff) progressively decreasing with increasing freeze-thaw cycles. Freeze-thaw cycles accelerated the propagation of microcracks within the rock specimens, leading to a gradual weakening of the peak characteristics in the fracture process zone. At high freeze-thaw cycles, the rate of decline slowed, indicating a transition in the rock failure mode from brittle fracture to ductile failure. The research results provide experimental data support for the safety design and stability evaluation of deep-frozen wellbore engineering.