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<p>The long-term stability of deep mining projects (≈800 m burial depth) relies on a fundamental understanding of the deformation and failure mechanisms of fractured rock masses under true triaxial stress in chemically corrosive environments. Through integrated true triaxial testing and acoustic emission (AE) monitoring, this study systematically investigates the coupled effects of chemical corrosion and the intermediate principal stress (<i>σ</i><sub>2</sub>) on the mechanical behavior, AE characteristics, and fracture evolution of flawed sandstone. The results indicate that: (1) chemical corrosion fundamentally degrades the rock matrix, with acidic conditions inducing the most severe weakening attributable to the synergistic effects of cement dissolution and secondary clay formation. Conversely, increasing <i>σ</i><sub>2</sub> exerts a competitive constraint that counteracts this deterioration, enhancing peak strength and stiffness while reducing material plasticity. (2) High <i>σ</i><sub>2</sub> confinement mechanistically governs crack propagation, evolving failure patterns from localized, flaw-controlled wing cracks to pervasive, stress-field-governed far-field fracture networks. Consequently, the macroscopic failure mode transitions from a mixed tensile-shear to a shear-dominant mechanism. This transition is quantitatively corroborated by RA-AF analysis (RA represents the ratio of rise time to amplitude, and AF denotes the average frequency), revealing a surge in the proportion of shear cracks to over 50% under high confinement. (3) The application of Plastic Strain Increments Ratio (PSIR) analysis demonstrates that the intermediate stress difference (<i>σ</i><sub>2</sub>—<i>σ</i><sub>3</sub>) drives plastic anisotropy. This anisotropy is characterized by preferential plastic extension in the least confined direction (<i>σ</i><sub>3</sub>) and restricted plastic extension along the <i>σ</i><sub>2</sub> direction, highlighting the strong inhibitory effect of <i>σ</i><sub>2</sub> on lateral strain development without entirely suppressing its extensional nature. Collectively, these findings establish a quantitative correlation between the directionality of 3D stress-induced brittle fracture and the corresponding volumetric response, advancing the mechanistic understanding of fracture evolution in chemically corroded rock under true triaxial conditions.</p>

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True‐triaxial deformation, cracking and strength failure characteristics of chemically corroded flawed sandstone

  • 期刊论文

  • 发表日期：

    2026年7月6日

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  • Bing-Lei Li,
  • Jia-Yao Jiang,
  • Yi Long,
  • Yao Lin,
  • Ming Jiang

摘要

The long-term stability of deep mining projects (≈800 m burial depth) relies on a fundamental understanding of the deformation and failure mechanisms of fractured rock masses under true triaxial stress in chemically corrosive environments. Through integrated true triaxial testing and acoustic emission (AE) monitoring, this study systematically investigates the coupled effects of chemical corrosion and the intermediate principal stress (σ2) on the mechanical behavior, AE characteristics, and fracture evolution of flawed sandstone. The results indicate that: (1) chemical corrosion fundamentally degrades the rock matrix, with acidic conditions inducing the most severe weakening attributable to the synergistic effects of cement dissolution and secondary clay formation. Conversely, increasing σ2 exerts a competitive constraint that counteracts this deterioration, enhancing peak strength and stiffness while reducing material plasticity. (2) High σ2 confinement mechanistically governs crack propagation, evolving failure patterns from localized, flaw-controlled wing cracks to pervasive, stress-field-governed far-field fracture networks. Consequently, the macroscopic failure mode transitions from a mixed tensile-shear to a shear-dominant mechanism. This transition is quantitatively corroborated by RA-AF analysis (RA represents the ratio of rise time to amplitude, and AF denotes the average frequency), revealing a surge in the proportion of shear cracks to over 50% under high confinement. (3) The application of Plastic Strain Increments Ratio (PSIR) analysis demonstrates that the intermediate stress difference (σ2—σ3) drives plastic anisotropy. This anisotropy is characterized by preferential plastic extension in the least confined direction (σ3) and restricted plastic extension along the σ2 direction, highlighting the strong inhibitory effect of σ2 on lateral strain development without entirely suppressing its extensional nature. Collectively, these findings establish a quantitative correlation between the directionality of 3D stress-induced brittle fracture and the corresponding volumetric response, advancing the mechanistic understanding of fracture evolution in chemically corroded rock under true triaxial conditions.