Xu Jun, Luo Sen, Xiao Xiaochun, Jin Jiaxu
School of Mechanics and Engineering, Liaoning Technical University, Fuxin, 123000, China.
School of Civil Engineering, Liaoning Technical University, Fuxin, 123000, China.
Sci Rep. 2024 Aug 1;14(1):17839. doi: 10.1038/s41598-024-68807-8.
To gain insights into the spatial distribution of non-penetrating cracks during the rock fracture process, a comprehensive uniaxial compression test is conducted on cubic gypsum specimens (100 mm × 100 mm × 100 mm) containing two non-penetrating cracks. The two pre-formed cracks are rectangular, with dimensions of 25 mm length, 2 mm width, and depths of 80 mm and 35 mm on adjacent sides of the specimen. The depth of the 80 mm crack can be adjusted from 0° to 150° in increments of 30°, while the other is fixed at a 45° angle. The results show that the spatial distribution of non-penetrating cracks can significantly influence the strength of the specimen. Initially, the strength of the specimen exhibits an upward trend and subsequently declines as the pre-crack inclination angle of the main rupture plane increases, ultimately reaching its pinnacle at 90°. The total percentage of tensile cracks in specimens with different inclinations are found to be 57%, 57%, 63%, 77%, 68%, and 61%, respectively. This change aligns seamlessly with the fluctuation in specimen strength as influenced by the angle of inclination. Non-penetrating cracks can also induce spalling on the specimen surface and give rise to anti-wing cracks, thereby exacerbating the spalling on the specimen surface. The inclinations of non-penetrating cracks can inevitably exert a certain influence on the propagation of neighboring non-penetrating cracks. Additionally, the macro-scale shear fracture of the specimen often occurs on the side of the non-penetrating crack that is deeper. The curved tensile fracture surface formed by the extension of the non-penetrating crack bears resemblance to the non-penetrating region in its ability to somewhat restrain the propagation of new cracks. Even under uniaxial compression, the spalling surface of the specimen containing spatial non-penetrating cracks frequently exhibits fracture characteristics belonging to I-III mode fracture, while its interior may display characteristics belonging to I-II-III mode fracture. These findings hold significant implications for comprehending and elucidating the genuine fracture process and three-dimensional fracture theory of rocks.
为深入了解岩石断裂过程中非贯通裂纹的空间分布情况，对含两条非贯通裂纹的立方体石膏试件（100 mm×100 mm×100 mm）进行了全面的单轴压缩试验。两条预制裂纹为矩形，长度25 mm，宽度2 mm，分别位于试件相邻两侧，深度分别为80 mm和35 mm。80 mm深裂纹的深度可在0°至150°范围内以30°为增量进行调整，另一条裂纹固定在45°角。结果表明，非贯通裂纹的空间分布会显著影响试件强度。起初，试件强度呈上升趋势，随后随着主破裂面预裂纹倾角的增大而下降，最终在90°时达到峰值。不同倾角试件中拉伸裂纹的总百分比分别为57%、57%、63%、77%、68%和61%。这一变化与试件强度受倾角影响的波动无缝契合。非贯通裂纹还会在试件表面诱发剥落并产生反翼裂纹，从而加剧试件表面的剥落。非贯通裂纹的倾角不可避免地会对相邻非贯通裂纹的扩展产生一定影响。此外，试件的宏观剪切断裂通常发生在非贯通裂纹较深的一侧。非贯通裂纹扩展形成的弯曲拉伸断裂面在一定程度上抑制新裂纹扩展的能力与非贯通区域相似。即使在单轴压缩下，含空间非贯通裂纹试件的剥落面也常呈现出属于Ⅰ - Ⅲ型断裂的断裂特征，而其内部可能呈现出属于Ⅰ - Ⅱ - Ⅲ型断裂的特征。这些发现对于理解和阐明岩石的真实断裂过程及三维断裂理论具有重要意义。
