为研究寒区岩体在冻融循环和疲劳荷载耦合作用下的损伤特性，开展单一裂隙大理岩冻融循环试验及核磁共振细观试验和不同围压下三轴压缩疲劳宏观试验，分析了冻融循环后裂隙大理岩的孔隙结构扩展特征及冻融循环与疲劳荷载作用下裂隙大理岩的力学特性和变形破坏特征。引入损伤变量，建立了冻融与疲劳荷载作用下基于西原蠕变模型的单一裂隙大理岩疲劳损伤本构模型。结果表明：随冻融次数增加，裂隙大理岩的质量损失率和纵波波速损失率均逐渐升高，核磁共振T₂曲线呈现出三峰特征，曲线整体右移，次峰与第三峰逐渐连接，峰总面积不断增大。围压与裂隙大理岩的疲劳强度呈正相关，随着围压的增大，裂隙大理岩的抗疲劳能力增加，延性增强，岩样破坏模式逐步由局部剪切破坏转变为整体剪切破坏。所建立的疲劳损伤本构模型理论曲线与试验数据基本吻合。研究结果可为寒区岩体工程灾害的防治提供参考依据。

To study the damage characteristics of rock masses in cold regions under the coupling effect of freeze-thaw cycles and fatigue loads, freeze-thaw cycle tests, nuclear magnetic resonance microscopic tests, and triaxial compression fatigue macroscopic tests under different confining pressures were carried out on single crack marble. The pore structure expansion characteristics of fissured marble after freeze-thaw cycles, as well as the mechanical properties and deformation failure characteristics of fissured marble under freeze-thaw cycles and fatigue loads were analyzed. A single crack marble fatigue damage constitutive model based on Nishihara creep model was established by introducing damage variables under freeze-thaw and fatigue loads. The results showed that with the increase of freeze-thaw cycles, the mass loss rate and longitudinal wave velocity loss rate of fissured marble gradually increased. The nuclear magnetic resonance T₂ curve showed a three peak characteristic, with the whole curve shifting to the right. The second peak gradually connected with the third peak, and the total peak area continued to increase. There was a positive correlation between confining pressure and the fatigue strength of fissured marble. With the increase of confining pressure, the fatigue resistance and ductility of fissured marble increased, and the failure mode of the rock sample gradually changed from local shear failure to overall shear failure. The theoretical curve of the established fatigue damage constitutive model was basically consistent with the experimental data. The research results could provide reference for the prevention and control of rock engineering disasters in cold regions.