## 1 Introduction  
According to the environmental objectives of the 2030 agenda for sustainable development, building infrastructure with disaster resilience, promoting inclusive and sustainable industrialization, and promoting innovation are the main objectives [1]. Slope stability is one of the main means of ensuring the ability of infrastructure to resist disasters. Landslides are the fourth most fatal natural disaster after floods, storms, and earthquakes. It has comprehensive coverage, high frequency, and incredible destructive power and can seriously endanger human life and property [1, 2, 3]. The evolution of landslides is closely related to geological structure conditions [2, 3], seismic activities [4, 5], rainfall [6], human activities [7], and other factors. The rock slope is an essential structure in hydropower engineering [8]. It plays a role in bearing the thrust of the dam and preventing water seepage [8, 9]. Due to complex geological processes, many joints are often developed in the rock slope, which threatens the slope's stability during construction and operation [6]. Under complex geological conditions in mountainous areas, the stability of the slope is affected by many factors. Based on the analysis and numerical analysis of the actual rock mass structure of the slope, the instability mechanism of the slope under the influence of the double factors of excavation and rainwater infiltration is studied, which has reference significance in the analysis of slope stability [10]. In slope engineering, the rock mass stress near the excavation face is redistributed due to the disturbance of excavation to the rock mass. Its mechanical characteristics are significant areas of unloading [11]. Unloading causes the rapid deterioration of rock mass quality [12]. Therefore, unloading should be considered in the stability analysis of unloaded rock slope [13]. Rock mass excavation must undergo the dynamic change process of unloading, deformation damage, and deterioration of rock mass mechanical conditions. Its dynamic stability in the excavation process is a problem worthy of study. After slope excavation, the rock mass is unloaded and damaged, the joint connectivity increases, and the rock mass quality deteriorates [8]. The unloading degree of rock mass in different areas is different, and with the progress of excavation, the unloading area and unloading degree of rock mass are constantly changing [9]. Therefore, the simulation process of unloading analysis should be a dynamic process of continuous adjustment [10]. [PERSON] et al. [14] took the three failure modes of the landslide in the Zigui basin of the Three Gorges Reservoir as an example to explain the main factors controlling the reservoir-induced landslide. The research results show that a low water level of 145 m to 155 m dramatically reduces the stability of the bank slope of the Three Gorges reservoir. [PERSON] et al. [15] conducted a series of uniaxial compression tests and conventional creep tests. The results showed that the stress cycle instantaneously increased the strain rate and promoted the sharpening of microcracks, thus improving the efficiency of stress corrosion cracking. [PERSON] et al. [9] conducted a numerical simulation based on the FLAC3D program to study the mechanisms and influencing factors of displacement mutation caused by blasting excavation. The results show that strain energy will accumulate and be stored in the slope rock mass under the compression of in situ stress. When blasting or excavation produces a free surface, the stored rock strain energy under in situ stress is released, resulting in joint opening and displacement mutation of the jointed rock slope. The magnitude of joint opening displacement is positively correlated with the strain energy release rate. [PERSON] et al.