## 4 Conclusions  
In this paper, from the perspective of the complex environment of cold region reservoir bank slopes undergoing unloading disturbance and seasonal freeze-thaw erosion, we conducted triaxial unloading tests simulating the excavation disturbance process and seasonal freeze-thaw environment simulation tests. Finally, the loading creep test was carried out based on the division of the confining pressure value and freezing periods, and we compared and analyzed the deformation behavior, damage characteristics, and strength characteristics of sandstone samples subjected to unloading disturbance and freeze-thaw deterioration. Some conclusions are drawn as follows:  
Figure 7: Isochronous curve cluster of the unloaded sample (where (**a**,**c**,**e**) and (**b**,**d**,**f**) are initial confining pressures of 15 MPa and 21 MPa, respectively). (**a**) R15-0. (**b**) R21-0. (**c**) R15-7. (**d**) R21-7. (**e**) R15-14. (**f**) R21-14. 1. During the unloading test, it was found that lateral expansion is the main form of unloading process. The degree of unloaded damage of rock samples is related to the stress level, the unloading response in the high stress state is more obvious, and the unloading process produces greater unrecoverable plastic damage. Therefore, the excavation and unloading process of rock in high ground stress areas should pay close attention to stress and lateral deformation monitoring to prevent the occurrence of engineering accidents such as rock bursts. 2. During the graded loading creep test, it was found that the degradation effect of freeze-thaw on unloaded rock samples is controlled by the unloading level. The unloading process provides an action channel for the intervention of the water-ice phase change. Compared with freeze-thaw action, the unloading process is the main control factor causing the structural damage of the rock. In addition, the lateral strain of unloaded granite under freeze-thaw action is greater than the axial strain because of the nature of the unloading process and the mechanism of the freeze-thaw action. 3. During the graded loading creep test, it was found that the creep strain was more significantly affected by the freeze-thaw action than the instantaneous strain, and it was related to the freezing period. Specifically, the creep rate under all levels of loading increases significantly when the freezing period increases. 4. During the graded loading creep test, it was found that the creep damage pattern of the unloaded sample is mainly manifested as shear damage. Under a low confining pressure, the brittle characteristics of the unloaded sample are obvious, tensile cracks are produced in addition to the main rupture surface, and the number of cracks increases significantly after the freeze-thaw action. As the confining pressure increases, the plastic characteristics of the unloaded sample are enhanced, the rupture morphology is mainly an oblique shear rupture surface, and a small number of secondary cracks are produced along the rupture surface after the freeze-thaw action. 5. During the graded loading creep test, it was found that the long-term strength of the unloaded sample is determined by the isochronous curve cluster method, and the calculation results show that the long-term strength of the sandstone decreases after the development of unloading damage and that the ratio of long-term strength to instantaneous strength is approximately 50-55%. The freeze-thaw action aggravates the structural damage of the unloaded sample, and the long-term strength of the unloaded sandstone gradually decreases and has a lower limit threshold with the extension of the freezing period. 6.