###### Abstract
In cold regions, the surface failure and collapse of steps are the common forms of damage to rock slopes in open-pit mines after repeated freezing and thawing processes over a long period of time. In Hokkaido, Japan, shallow damage to rock slopes occurs frequently, with an average depth of 2-3 m [30]. The depth of the frozen layer in open-pit mines in cold regions is affected by factors such as latitude, altitude, and climatic conditions. Natural disasters caused by freezing and thawing often occur in cold-zone mines both domestically and abroad, which seriously threaten the safe production of mines. For example, the slope instability of open-pit mines in the Wardha Valley Coalfield in central India [31], the permafrost ablation landslides in the Caucasus region of Russia [30], the landslides in the British Columbia region of Canada [32], the freezing and thawing landslides in the Punta Thurwieser region of Italy [33], and the deformation and instability of permafrost slopes in the Muli Coal Mine in China [34] are all examples of such natural disasters. [PERSON] et al. [35] conducted an in-depth study of the damage patterns of frozen rock slopes in the Muli Juhuqian mine through on-site investigations and found that the damage patterns of frozen rock slopes are mainly characterized by progressive damage in the upper part of the slopes. [PERSON] et al. [36] used a simplified algorithm of temperature, seepage, and stress field coupling (THM) with phase change to investigate the local damage evolution of mine slopes under the action of freezing and thawing and discussed the operability of local stability analysis based on yield proximity and based on this, they discussed the influence of different factors on the stability of slopes. A percentage of 80% of China's open-pit coal mines are located in Inner Mongolia, Xinjiang, and other northern regions [37], where the seasonal temperature difference is large, and the slopes of the water-bearing drainage field will show obvious characteristics of freeze-thaw cycle [38; 39]. The freeze-thaw cycle will have a huge impact on the slope stability of the discharge site, and the risk of landslides and slides will increase, seriously threatening the safety and stability of the open-pit mine discharge site [40]. The Baorixile outer soil discharge field is located in the north, composed of a long low temperature and long existence time, which will be damaged and deteriorate to a certain extent after undergoing a freeze-thaw cycle. At present, as a kind of complex bulk material, there have been numerous studies on the differences in its internal structure, but the research on the damage characteristics of soil-stone mixtures after the freeze-thaw cycle and the stability of soil-stone mixture slopes in the external soil discharge site after the freeze-thaw cycle has just begun. Therefore, this paper takes the Baorixile open-pit coal mine as the study background, carries out research on the damage characteristics and slope stability of soil-rock mixture slopes in the external discharge field, and analyzes the stability of soil-rock mixture slopes after undergoing freeze-thaw cycles. This is conducted using indoor experiments on soil-rock mixtures in different freeze-thaw cycles and numerical simulation software (PFC5.0) to explore the influence of freeze-thaw cycles on soil-rock mixture slopes and to provide the best solution for the slope safety of the external discharge field in open-pit coal mines. The slope safety of the external discharge site provides the basis.