Abstract The artificial freezing method is an effective method of shaft construction in water-rich soft rock beds. Engineering frozen walls involves the use of intact rock material, flaws and ice. To better understand the mechanical properties of frozen walls, explore the failure laws of frozen fractured rock, and solve the problem of complex ice-rock coupling, it is necessary to carry out laboratory triaxial tests on frozen fractured rock. Herein, X-ray diffraction and mesostructure observations are used to analyse the mineral composition and microstructural characteristics of red sandstone specimens taken from the Shilawusu coal mine. Then, the strength, deformation and crack evolution behaviour of red sandstone containing two pre-existing ice-filled fissures are obtained under triaxial compression using the self-developed DRTS−500 subzero rock triaxial testing system. The experimental results show that the peak strength and elastic modulus of the specimens with pre-existing flaws are all much lower than those of the intact specimens, and the strength parameters are distinctly related to the flaw combinations. For the frozen red sandstone containing two intermittent ice-filled fissures, the peak strength, elastic modulus and shear strength parameters all have a linear relationship with the confining pressure and temperature, whereas the shear strength (σ1 − σ3) has a nonlinear relationship with the confining pressure. The deviatoric stress-strain curve of the samples is divided by four characteristic stresses (compacting stress, crack initiation stress, dilatancy stress and peak stress) into five stages from loading to failure. The lower the confining pressure or temperature is, the faster the curve falls after reaching the stress-strain peak value, indicating that the sample exhibits increasingly brittle characteristics. The ultimate failure modes of the specimens containing two pre-existing ice-filled flaws include mixtures of several types of cracks (shear cracks, main cracks, secondary cracks, tensile cracks, coplanar cracks, slip cracks and wing cracks), which depend on the flaw combinations. An obvious crack coalescence failure mode can be observed in the GG and GS specimens, but no obvious crack coalescence phenomenon can be observed in the SS specimens.

中文翻译：

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三轴压缩下含两条冰裂隙的红砂岩样品强度、变形及裂纹演化行为试验研究

摘要 人工冻结法是富水软岩层竖井施工的有效方法。工程冷冻墙涉及使用完整的岩石材料、裂缝和冰。为了更好地了解冻结壁的力学特性，探索冻结裂隙岩的破坏规律，解决复杂的冰岩耦合问题，有必要对冻结裂隙岩进行室内三轴试验。本文利用X射线衍射和细观结构观察分析了石拉乌苏煤矿红砂岩标本的矿物组成和显微结构特征。那么，实力，使用自主研发的DRTS-500零下岩石三轴试验系统，在三轴压缩下获得了含有两个预先存在的冰裂隙的红砂岩的变形和裂缝演化行为。实验结果表明，已有裂纹试样的峰值强度和弹性模量均远低于完整试样，且强度参数与裂纹组合有明显的相关性。对于含有两条间断充冰裂缝的冻结红砂岩，其峰值强度、弹性模量和剪切强度参数均与围压和温度呈线性关系，而剪切强度（σ1−σ3）与围压和温度呈非线性关系。围压。样品的偏应力-应变曲线被四个特征应力（压实应力、裂纹萌生应力、剪胀应力和峰值应力）分为从加载到破坏的五个阶段。围压或温度越低，曲线达到应力-应变峰值后下降越快，表明样品表现出越来越脆的特性。包含两个预先存在的充冰裂纹的试样的最终破坏模式包括几种类型裂纹（剪切裂纹、主裂纹、二次裂纹、拉伸裂纹、共面裂纹、滑动裂纹和翼裂纹）的混合，这取决于缺陷组合。在GG和GS试样中可以观察到明显的裂纹合并破坏模式，而在SS试样中没有观察到明显的裂纹合并现象。