Abstract Rocks in civil and mining engineering usually experience rather complex stress disturbance. Rock dynamic mechanical behaviors under constant stress amplitude condition have been widely studied. However, the rock fracture evolution characteristics subjected to multi-level cyclic loading conditions are not well understood. In this work, multi-level cyclic compressive loading experiments were performed on marble with interbed orientation of 0°, 30°, 60° and 90°. Anisotropic fracture evolution characteristics were revealed using dynamic stress strain descriptions and post-test CT scanning technique. Results show that rock fatigue deformation, strength, lifetime, dynamic elastic modulus and damping ratio are all impacted by rock structure. The interbed structure plays a dominant role in fracture evolution compared with natural fracture and pyrite band. Rock stiffness degrades and damping ratio increases with the increase of interbed orientation. In addition, a two-phase damage accumulation pattern was found for marble under multi-level cyclic loading condition. A damage evolution model was first established to model damage accumulation, the proposed model fits well to the experimental data. Moreover, post-test CT scanning reveals the internal crack coalescence pattern and failure mode is impacted by the interactions of interbeds, natural fracture and pyrite bands. The rock bridge structure in marble with 60° and 90° interbed orientation alters the crack propagation path. Although the crack pattern is relatively simple at rock bridge segment, much more energy is needed to drive crack propagation. The testing results are expected to improve the understanding of the influence of rock structure on fracture evolution when subjected to variable stress amplitude loading conditions.

中文翻译：

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多级单轴压缩循环加载条件下互层大理石的动态力学行为：对断裂演化分析的洞察

摘要 土木和采矿工程中的岩石通常会经历比较复杂的应力扰动。恒应力幅条件下的岩石动态力学行为已得到广泛研究。然而，在多级循环加载条件下岩石断裂演化特征还不是很清楚。在这项工作中，对夹层方向为0°、30°、60°和90°的大理石进行了多级循环压缩加载实验。使用动态应力应变描述和测试后 CT 扫描技术揭示了各向异性裂缝演化特征。结果表明，岩石的疲劳变形、强度、寿命、动弹性模量和阻尼比均受岩石结构的影响。与天然裂缝和黄铁矿带相比，夹层结构在裂缝演化中起主导作用。随着夹层取向的增加，岩石刚度降低，阻尼比增加。此外，还发现了多级循环加载条件下大理石的两相损伤累积模式。首先建立损伤演化模型对损伤累积进行建模，该模型与实验数据拟合良好。此外，测试后 CT 扫描显示内部裂纹合并模式和破坏模式受夹层、天然裂缝和黄铁矿带相互作用的影响。大理岩中 60° 和 90° 夹层取向的岩桥结构改变了裂纹扩展路径。虽然岩桥段的裂缝模式比较简单，需要更多的能量来驱动裂纹扩展。测试结果有望提高对岩石结构在可变应力幅加载条件下对裂缝演化影响的理解。