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<p>To address the failure and instability of pre-existing fissure sandstone under cyclic loading conditions, this study employed multi-level incremental cyclic loading (MLICL) tests and acoustic emission (AE) monitoring techniques to investigate the deformation response, crack evolution, and damage accumulation characteristics. Wave velocity tomography and damage visualization were achieved using anisotropic medium theory and Fast Marching Method (FMM) ray tracing, revealing the influence patterns of pre-existing fissures at different inclination angles on sandstone mechanical response, fracture mechanisms, and damage evolution. Systematic analysis of the spatiotemporal evolution characteristics of crack development in specimens with 0°–90° pre-existing fissures demonstrates that pre-existing fissures significantly alter the load-bearing capacity and deformation characteristics of sandstone. Intact specimens achieved peak strength of 78&#xa0;MPa, whereas fissured specimens exhibited reduced strengths ranging from 34 to 46&#xa0;MPa. The influence of fissure inclination angle on mechanical properties exhibits complex nonlinear characteristics: 0° horizontal fissures generate the highest damage values and AE event counts, followed by 60° fissures, while 45° and 90° fissures exerted relatively minor effects. Moment tensor analysis reveals that shear failure dominates at 30° inclination, mixed-mode failure becomes more prominent at 60° inclination, and tensile failure becomes more significant at 90° inclination. The spatiotemporal evolution characteristics of progressive damage accumulation throughout the experimental process were revealed, exhibiting rapid increase during the later loading stages. A constitutive equation describing the dynamic damage evolution throughout the MLICL experimental process was established, with experimental data demonstrating excellent agreement with theoretical curves. Parameter sensitivity analysis further confirms the reliability of this equation. Additionally, a strong positive correlation between damage degree and AE activity intensity was revealed, which was further validated by digital image correlation (DIC) strain field measurements. Compared to traditional post-processing methods based on cumulative parameters, damage calculation based on wave velocity inversion achieves real-time monitoring capability, providing effective technical approaches for rock failure early warning systems.</p>

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AE Characteristics and Dynamic Damage Evolution of Fissured Sandstone Under Multi-level Cyclic Loading Using Wave-Velocity Tomography

  • 期刊论文

  • 发表日期：

    2026年2月19日

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  • Cheng Lyu,
  • Kai Liu,
  • Wuqiang Cai,
  • Zhiwei Yan,
  • Xiongyu Hu,
  • Jiadi Wen,
  • Zecan Chen,
  • Binbin Miao

摘要

To address the failure and instability of pre-existing fissure sandstone under cyclic loading conditions, this study employed multi-level incremental cyclic loading (MLICL) tests and acoustic emission (AE) monitoring techniques to investigate the deformation response, crack evolution, and damage accumulation characteristics. Wave velocity tomography and damage visualization were achieved using anisotropic medium theory and Fast Marching Method (FMM) ray tracing, revealing the influence patterns of pre-existing fissures at different inclination angles on sandstone mechanical response, fracture mechanisms, and damage evolution. Systematic analysis of the spatiotemporal evolution characteristics of crack development in specimens with 0°–90° pre-existing fissures demonstrates that pre-existing fissures significantly alter the load-bearing capacity and deformation characteristics of sandstone. Intact specimens achieved peak strength of 78 MPa, whereas fissured specimens exhibited reduced strengths ranging from 34 to 46 MPa. The influence of fissure inclination angle on mechanical properties exhibits complex nonlinear characteristics: 0° horizontal fissures generate the highest damage values and AE event counts, followed by 60° fissures, while 45° and 90° fissures exerted relatively minor effects. Moment tensor analysis reveals that shear failure dominates at 30° inclination, mixed-mode failure becomes more prominent at 60° inclination, and tensile failure becomes more significant at 90° inclination. The spatiotemporal evolution characteristics of progressive damage accumulation throughout the experimental process were revealed, exhibiting rapid increase during the later loading stages. A constitutive equation describing the dynamic damage evolution throughout the MLICL experimental process was established, with experimental data demonstrating excellent agreement with theoretical curves. Parameter sensitivity analysis further confirms the reliability of this equation. Additionally, a strong positive correlation between damage degree and AE activity intensity was revealed, which was further validated by digital image correlation (DIC) strain field measurements. Compared to traditional post-processing methods based on cumulative parameters, damage calculation based on wave velocity inversion achieves real-time monitoring capability, providing effective technical approaches for rock failure early warning systems.