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<p>For rock engineering structures in cold and high-altitude regions, rock mass is often subjected to the coupling action of freeze–thaw (F–T) and cyclic shear loading. Rock’s fracture behavior and energy evolution characteristics under room temperature and cyclic or fatigue loading have been extensively studied, mainly focusing on the compression properties of rocks. However, the investigations into shear characteristics of rocks subjected to sub-zero temperature and cyclic shear loading are relatively rare. Therefore, in this paper, a series of tangential multilevel cyclic shear loading tests under a constant normal stress of 2&#xa0;MPa are conducted on fractured sandstone specimens with F–T treatment of 0, 20, 40, 60, and 80 cycles to explore the energy dissipation mechanism of the rock, damage evolution, and failure characteristics. The results show that the three energy densities increase in a quadratic polynomial law with the number of cycles, while during the final cyclic loading stage, they indicate a three-stage trend with the number of F–T cycles. A linear energy storage and dissipation law of rock specimens is observed during the multilevel cyclic shear loading process; in addition, the F–T-cyclic shear coupling damage model is developed based on the Lemaitre strain equivalence principle. The damage accumulation curve shows a cubic polynomial growth with the number of cycles, and the growth rate is fast at first, then slow in the middle stage, and faster later. Moreover, the macroscopic deformation evolution and failure modes of the specimens are further revealed.</p>

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Failure Mechanism of Fractured Sandstone Subjected to Cyclic Freeze–Thaw and Shear Loading

  • 期刊论文

  • 发表日期：

    2026年6月3日

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  • Taoying Liu,
  • Tao Zhang,
  • Min Tang,
  • Mengyuan Cui,
  • Longjun Dong,
  • Shaowei Ma

摘要

For rock engineering structures in cold and high-altitude regions, rock mass is often subjected to the coupling action of freeze–thaw (F–T) and cyclic shear loading. Rock’s fracture behavior and energy evolution characteristics under room temperature and cyclic or fatigue loading have been extensively studied, mainly focusing on the compression properties of rocks. However, the investigations into shear characteristics of rocks subjected to sub-zero temperature and cyclic shear loading are relatively rare. Therefore, in this paper, a series of tangential multilevel cyclic shear loading tests under a constant normal stress of 2 MPa are conducted on fractured sandstone specimens with F–T treatment of 0, 20, 40, 60, and 80 cycles to explore the energy dissipation mechanism of the rock, damage evolution, and failure characteristics. The results show that the three energy densities increase in a quadratic polynomial law with the number of cycles, while during the final cyclic loading stage, they indicate a three-stage trend with the number of F–T cycles. A linear energy storage and dissipation law of rock specimens is observed during the multilevel cyclic shear loading process; in addition, the F–T-cyclic shear coupling damage model is developed based on the Lemaitre strain equivalence principle. The damage accumulation curve shows a cubic polynomial growth with the number of cycles, and the growth rate is fast at first, then slow in the middle stage, and faster later. Moreover, the macroscopic deformation evolution and failure modes of the specimens are further revealed.