Abstract For rock engineering in cold regions, rock is often subjected to coupled fatigue conditions of freeze-thaw (F-T) and stress disturbance. Rock fracture evolution and energy mechanism under room temperature and constant stress amplitude loading condition have been widely investigated. Yet the rock energy dissipation and damage evolution characteristics subjected to multiple level cyclic loading conditions are not well understood. In this work, multiple level cyclic compressive loading experiments were conducted using GCTS RTR 2000 rock mechanics system on marble with F-T treatment of 0, 20, 40 and 60 cycles. The fracture evolution and energy dissipation mechanism were analyzed as well as the damage evolution characteristics. The results indicate that F-T treatment strongly influences the fatigue mechanical behaviors of marble, with both fatigue strength and strain energy decreases and irreversible volumetric deformation increases with increasing F-T cycles. The incremental rate of dissipated energy becomes faster as cyclic loading level grows. In addition, a F-T-fatigue loads coupling damage variable was proposed by using the input total strain energy and the dissipated strain energy to describe the rock damage evolution after F-T treatment and experiencing fatigue loading. Moreover, a damage evolution model was first established based on the obtained coupling damage variable to describe the two-phase damage accumulation characteristics. Damage accumulation curve presents a first steady increase and then faster increase trend, the damage evolution model can good fit the experimental data.

中文翻译：

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冻融和多级压缩疲劳载荷作用下大理石动态断裂的能量耗散与损伤演化

摘要 在寒冷地区的岩石工程中，岩石经常受到冻融（FT）和应力扰动的耦合疲劳工况。常温恒应力幅加载条件下的岩石断裂演化和能量机制已得到广泛研究。然而，在多级循环加载条件下岩石能量耗散和损伤演化特征还不是很清楚。在这项工作中，使用 GCTS RTR 2000 岩石力学系统对大理石进行了多级循环压缩加载实验，FT 处理为 0、20、40 和 60 次循环。分析了断裂演化和能量耗散机制以及损伤演化特征。结果表明，FT 处理对大理石的疲劳力学行为有很大影响，随着疲劳强度和应变能的降低，不可逆的体积变形随着 FT 循环次数的增加而增加。随着循环负载水平的增加，耗散能量的增量速率变得更快。此外，通过使用输入总应变能和耗散应变能来描述FT处理和经历疲劳载荷后岩石损伤演化，提出了FT-疲劳载荷耦合损伤变量。此外，首先基于获得的耦合损伤变量建立损伤演化模型来描述两相损伤累积特性。损伤累积曲线呈现先稳定增大后较快增大的趋势，损伤演化模型与实验数据拟合较好。