Geomechanical studies of rock salt serve as the foundation for designing and ensuring the long-term stability of storage caverns. Research conducted in recent years has shown that rock salt exhibit highly variable mechanical parameters. Even macroscopically similar rock salt samples from the same formation have very different mechanical parameters in standard strength tests. In this paper, the effect of microfabrics on the mechanical behaviour of rock salt was studied using a uniaxial compression device with simultaneous observation under a microscope. The tests were carried out on rock salt samples, previously tested on standard uniaxial compression (UCS). Tested samples showed different strength values despite macroscopic similarity and similar anhydrite content. The tests revealed that the microfabrics, such as fluid inclusions and anhydrite crystals distributed along the halite grain boundaries, play a significant role in the strength of a rock salt sample. Four types of grain boundaries were recognized in both group of samples: (1) dominated by anhydrite crystals with a small number of fluid inclusions (FIs), (2) with FIs prevailing over anhydrite crystals, (3) only with FIs, and (4) without anhydrite crystals or FIs. The experimental uniaxial compression tests in microscale (mUCS) showed that the damage process is initiated by FIs activity at the halite grain boundaries and consists of three main stages. The samples dominated by anhydrite crystals at halite grain boundaries were characterised by the highest mUCS. Conversely, if FIs prevail at the grain boundaries the lowest mUCS values were registered. Therefore, anhydrite crystals located along halite grain boundaries influenced the mechanical behaviour and deformation process. On the contrary, anhydrite crystals dispersed within halite grains had no impact on failure and mechanical parameters. The experiment showed that apart from impurity content, the distribution of these impurities within halite grains should be examined during geomechanical evaluation of rock salt samples. Thus, the overall strength of rock salt samples determined in standard test results from the local variations of petrological features in micro- and macro scale.

中文翻译：

---

微纤维对岩盐地质力学多样性的影响——实验研究


岩盐地质力学研究是设计和确保储存洞穴长期稳定性的基础。近年来进行的研究表明，岩盐表现出高度可变的机械参数。即使来自同一地层的宏观相似的岩盐样品在标准强度测试中也具有非常不同的机械参数。本文利用单轴压缩装置并在显微镜下同时观察，研究了微纤维对岩盐力学行为的影响。这些测试是在岩盐样品上进行的，之前是在标准单轴压缩 (UCS) 上进行测试的。尽管宏观相似且硬石膏含量相似，但测试样品显示出不同的强度值。测试表明，沿着岩盐晶界分布的微结构，例如流体包裹体和硬石膏晶体，对岩盐样品的强度起着重要作用。在两组样品中均发现了四种类型的晶界：(1) 以硬石膏晶体为主，并含有少量流体包裹体 (FI)；(2) FI 多于硬石膏晶体；(3) 仅含有 FI；( 4) 不含硬石膏晶体或 FI。微尺度单轴压缩实验（mUCS）表明，损伤过程是由岩盐晶界处的FIs活动引发的，并由三个主要阶段组成。以石盐晶界处的硬石膏晶体为主的样品具有最高的 mUCS 特征。相反，如果 FI 在晶界处占主导地位，则记录最低 mUCS 值。因此，沿着石盐晶界分布的硬石膏晶体影响了力学行为和变形过程。 相反，分散在岩盐颗粒内的硬石膏晶体对失效和机械参数没有影响。实验表明，在对岩盐样品进行地质力学评价时，除了杂质含量外，还应检查这些杂质在岩盐颗粒内的分布。因此，标准测试中确定的岩盐样品的整体强度是根据微观和宏观尺度岩石学特征的局部变化得出的。