## 1 Introduction  
With the increasing mining depth of medium and large open-pit mines, a number of high and steep slopes are inevitably formed. The stability of these slopes poses a huge hidden danger to the daily functioning of mines and to the safety of the lives and property of construction personnel [1, 2]. There are many unfavorable factors affecting the safety and stability of open-pit mine slopes [3, 4, 5]. First of all, the traditional method of geological surveying requires manual standing at the foot of the open-pit slope and using geological survey tools such as a compass and measuring tape to measure and record on site, which requires the participation of many people and requires a large survey area, resulting in low survey efficiency. The general height of the slope of the open-pit mine is large, and the height of the slope after merging sections is often as high as 30 m, while manual measurements can only be carried out within a very limited range of 2-3 m at the top of the slope. The structural surface measured is not very representative. On-sitesurveyors stand under the slope for a long time, but the upper part of the slope is affected by high wind, self-weight, and production activities, and there is a risk of falling pumice, which poses a great threat to the safety of on-site surveyors, often impeding the ability to conduct geological investigations. Secondly, the risks posed to slope safety by blasting vibrations generated in the process of mine production cannot be ignored [6; 7; 8]. As open-pit mining becomes increasingly challenging, its mining costs are rising, prompting many mines to transition from open-pit mining to combined open-pit and underground mining. Underground mining destroys the original geological structure, and the influence of the leftover goal on slope stability needs to be studied [9; 10; 11; 12]. Therefore, it is necessary to study the influence of the goaf on slope stability. In conjunction with the current mining situation, the research and evaluation of mine slope stability is a major concern for ensuring the safety of mine production. By carrying out investigation and test analysis on the slope of the excavated area, the current slope stability situation and the potential landslide risk in the lower mining process are further analyzed and evaluated. This study provides beneficial recommendations and guidance for the subsequent safe working of the mine, and it makes a significant contribution to the safety, damage prevention, and control of the mine slope, as well as to efficient deep mining. The study of slope stability is based on the study of the rock mass structure. The development degree of the structural plane seriously affects the stability of the slope rock mass. Although traditional geological survey methods, such as the survey line method and the window statistics method, are more accurate, the efficiency is low and the workload is large [13]. In order to solve these problems, the method of using three-dimensional laser scanning [14; 15] and UAV mapping technology for geological surveying and structural plane information acquisition has gradually emerged; this method provides significant benefits to slope engineering geological surveys. Among them, aerial survey technology with small UAVs has been rapidly applied, and has a broad prospect of widely implemented applications in major engineering construction, mining resource development, land monitoring, disaster emergency and treatment, geological survey and mapping, digital city construction, et cetera [16; 17; 18]. In 2014, [PERSON] et al. [19] studied the measurement data of rock based on UAV aerial images and developed a photogrammetric dataset that can be used to generate the rock surface by UAV aerial images. [PERSON] et al. [20] used UAV aerial images to generate a digital grid of the rock mass and obtained the geometric parameters of the grid, and further compared the differences between the geometric parameters collected by the UAV and the actual project. [PERSON] et al.