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<p>Blasting excavation and mechanical vibration in underground engineering often induce “three-dimension (3D) stress + dynamic disturbance” coupled failure of rockmass structural planes, leading to engineering disasters. However, the disturbance effects on rockmass structural planes under 3D stress are unclear. Therefore, true triaxial shear disturbance tests with different amplitude (<i>A</i>) and frequency (<i>f</i>) were carried on limestone structural planes with acoustic emission (AE) monitoring. The effects of <i>A</i> and <i>f</i> on mechanical properties and failure characteristics were systematically studied. The disturbance damage evolution and energy release characteristics, shear fracture evolution process, microscopic fracture mechanisms, and failure precursor were further revealed. As the <i>A</i> and <i>f</i> increase, the shear failure stress and critical strength of limestone structural planes rapidly decrease and then converge. As the <i>A</i> increases, the disturbance strain energy (<i>U</i>) at failure significantly increases, the proportion of dissipated energy (<i>U</i><sup>d</sup>) changes little, while as the <i>f</i> increases, the <i>U</i> at failure gradually decreases, the proportion of <i>U</i><sup>d</sup> increases. Furthermore, through the analysis of AE signals, the failure mechanism of limestone structural planes is primarily the shear–tensile mixed failure mode dominated by tensile cracks. As the shear stress increases, the proportion of shear cracks gradually increases. As the <i>A</i> increases, the proportion of shear cracks first decreases slightly and then increases significantly. As failure approaches, the number of AE events increases rapidly, with a large number of high-energy events occur mainly focusing on shear failure surfaces, especially as the <i>A</i> increases, the trendy become more pronounced. Near the failure, the <i>b-</i>value shows a continuous and significant downward trend, reaching the minimum at the time of failure, the high <i>A</i> signal increases significantly, and the fractal dimension (<i>D</i><sub>t</sub>) decreases rapidly to the minimum. The variation in lg<i>N/b</i> is opposite to that of the <i>b-</i>value, but remains relatively stable during the early stages of failure, with more pronounced changes at failure, which makes it a more suitable indicator for shear failure precursors.</p>

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Effects of Amplitude and Frequency on Shear Behaviors and Mechanisms of Limestone Structural Planes Under True Triaxial Stress

  • 期刊论文

  • 发表日期：

    2025年3月10日

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  • Zhi Zheng,
  • Xiangmeng Meng,
  • Guangliang Feng,
  • Gaoming Lu,
  • Xiaochuan Hu,
  • Wenjing Niu,
  • Xiaohua Huang

摘要

Blasting excavation and mechanical vibration in underground engineering often induce “three-dimension (3D) stress + dynamic disturbance” coupled failure of rockmass structural planes, leading to engineering disasters. However, the disturbance effects on rockmass structural planes under 3D stress are unclear. Therefore, true triaxial shear disturbance tests with different amplitude (A) and frequency (f) were carried on limestone structural planes with acoustic emission (AE) monitoring. The effects of A and f on mechanical properties and failure characteristics were systematically studied. The disturbance damage evolution and energy release characteristics, shear fracture evolution process, microscopic fracture mechanisms, and failure precursor were further revealed. As the A and f increase, the shear failure stress and critical strength of limestone structural planes rapidly decrease and then converge. As the A increases, the disturbance strain energy (U) at failure significantly increases, the proportion of dissipated energy (Ud) changes little, while as the f increases, the U at failure gradually decreases, the proportion of Ud increases. Furthermore, through the analysis of AE signals, the failure mechanism of limestone structural planes is primarily the shear–tensile mixed failure mode dominated by tensile cracks. As the shear stress increases, the proportion of shear cracks gradually increases. As the A increases, the proportion of shear cracks first decreases slightly and then increases significantly. As failure approaches, the number of AE events increases rapidly, with a large number of high-energy events occur mainly focusing on shear failure surfaces, especially as the A increases, the trendy become more pronounced. Near the failure, the b-value shows a continuous and significant downward trend, reaching the minimum at the time of failure, the high A signal increases significantly, and the fractal dimension (Dt) decreases rapidly to the minimum. The variation in lgN/b is opposite to that of the b-value, but remains relatively stable during the early stages of failure, with more pronounced changes at failure, which makes it a more suitable indicator for shear failure precursors.