Foamed polyurethane (PU) grouting materials are widely used for the non-destructive rehabilitation of roadbeds due to their expansion characteristics, lightweight, and high strength. However, their compressive fatigue resistance is still unclear. In this work, the relationships between density and strength/modulus were established by uniaxial compression tests. The fatigue damage evolution was divided into three stages by cyclic compression tests: adjustment stage, stable change stage, and cyclic failure or cyclic hardening stage. At high stress levels, the stiffness damage, deformation damage, maximum strain, and loss factor increased to about 16.07%, 60.14%, 5.25%, and 0.044 respectively after adjustment and stable change. Broken cells and cracks were observed in SEM images after cyclic failure. At low stress levels, the deformation damage is within the elastic range. The stiffness damage and loss factor always varied at a lower level and even tended to decrease. Obvious cracks were not observed in SEM images after cyclic hardening. The conclusion was drawn that density was the main factor affecting the compression fatigue performance of PU grouting materials, and high stress levels were the main reason for cyclic failure under the same density condition. Moreover, there was a functional relationship between the stress level and fatigue life of PU grouting materials. Some descriptions have been added in the revised manuscript.

发泡聚氨酯（PU）灌浆材料以其膨胀特性、轻质、高强等优点被广泛用于路基的无损修复。然而，它们的抗压疲劳性仍不清楚。在这项工作中，密度和强度/模量之间的关系是通过单轴压缩试验建立的。循环压缩试验将疲劳损伤演化分为三个阶段：调整阶段、稳定变化阶段、循环失效或循环硬化阶段。在高应力水平下，刚度损伤、变形损伤、最大应变和损耗因子经过调整和稳定变化后分别增加到约16.07%、60.14%、5.25%和0.044。循环失效后在 SEM 图像中观察到破裂的细胞和裂纹。在低压力水平下，变形破坏在弹性范围内。刚度损伤和损耗因子始终在较低水平上变化，甚至呈下降趋势。循环硬化后在SEM图像中未观察到明显裂纹。得出结论：密度是影响PU灌浆材料压缩疲劳性能的主要因素，在相同密度条件下，高应力水平是循环破坏的主要原因。此外，PU灌浆材料的应力水平与疲劳寿命之间存在函数关系。修改后的手稿中增加了一些描述。得出结论：密度是影响PU灌浆材料压缩疲劳性能的主要因素，在相同密度条件下，高应力水平是循环破坏的主要原因。此外，PU灌浆材料的应力水平与疲劳寿命之间存在函数关系。修改后的手稿中增加了一些描述。得出结论：密度是影响PU灌浆材料压缩疲劳性能的主要因素，在相同密度条件下，高应力水平是循环破坏的主要原因。此外，PU灌浆材料的应力水平与疲劳寿命之间存在函数关系。修改后的手稿中增加了一些描述。