Abstract The mechanical, acoustic, and fracture behaviors of sandstone play important roles in design and stability analysis in rock engineering applications. In this research, a series of triaxial monotonic and cyclic tests was conducted on yellow sandstone. The results of triaxial monotonic experiments were used to analyze the influence of the confining pressure on the mechanical parameters of the sandstone. The strength and deformation parameters depended strongly on the confining pressure. The triaxial strength of the sandstone specimens under cyclic loading was approximately equal to that under monotonic loading, whereas the fatigue loading led to a reduction in triaxial strength. Under lower deviatoric stress levels, the specimen was highly resistant to fatigue loading; however, higher deviatoric stress level lead to fatigue failure of the specimen even though after large cycle numbers. The influence of the cycle number on the deformation and crack damage parameters of the sandstone was also investigated. The internal damage of the sandstone specimens were characterized on basis of the recorded P-wave velocity and acoustic emission (AE) counts during triaxial monotonic loading, and the effect of the cycle number on the AE behaviors was explored under triaxial cyclic loading. Finally, the fractured yellow sandstone specimens were further analyzed by using X-ray micro computerized tomography (CT) scanning. The internal fracture characteristics of the sandstone specimens were investigated by cross-section analysis and three-dimentional (3D) reconstruction of the CT scanning, which revealed the fracture mechanism of the sandstone.

中文翻译：

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三轴单调循环加载下黄砂岩试样的力学、声学和断裂行为

摘要 砂岩的力学、声学和断裂行为在岩石工程应用中的设计和稳定性分析中起着重要作用。本研究对黄砂岩进行了一系列三轴单调循环试验。利用三轴单调试验结果分析围压对砂岩力学参数的影响。强度和变形参数很大程度上取决于围压。砂岩试样在循环加载下的三轴强度与单调加载下的三轴强度大致相等，而疲劳加载导致三轴强度降低。在较低的偏应力水平下，试样具有很强的抗疲劳载荷能力；然而，即使在大循环次数之后，较高的偏应力水平也会导致试样的疲劳失效。还研究了循环次数对砂岩变形和裂纹损伤参数的影响。根据三轴单调加载过程中记录的 P 波速度和声发射 (AE) 计数来表征砂岩试样的内部损伤，并在三轴循环加载下探索循环次数对 AE 行为的影响。最后，使用 X 射线显微计算机断层扫描 (CT) 扫描进一步分析破裂的黄砂岩标本。通过横截面分析和CT扫描的三维（3D）重建研究了砂岩标本的内部断裂特征，