## 2 Study Area  
Guizhou Province is located on the Yunnan-Guizhou Plateau in southwestern China and covers an area of 176,000 square km. The study area encompasses nine districts of Guizhou: Guiyang (GY), Zunyi (ZY), Liupanshui (LPS), Anshun (AS), Bijie (BJ), Tongren (TR), Qiandongnan Miao and Dong (QDN), Qiannan Buyei and Miao (QN), and Qianxian Buyei and Miao (QN). The average elevation of Guizhou is about 1000 m above sea level, and the terrain is undulating, with the height difference between the highest and the lowest point reaching 2763 m. Guizhou is characterized by mountainous areas, with the mountainous areas accounting for 90% of the province's area. Guizhou is widely distributed with karst landscapes [38]. Guizhou Province has a plateau-type subtropical climate with abundant rainfall, and the average annual rainfall is mostly between 1100 and 1400 millimeters [39]. The unique topography and climatic conditions of Guizhou Province provide excellent preconditions for the occurrence of natural disasters such as rockfalls and collapses. The study area for the entire Guizhou Province is shown in Figure 1.  
The stratigraphy of Guizhou is well developed, and is primarily associated with the Yangtze stratum. This region is predominantly characterized by extensive sedimentary rock formations, with limestone and shale being the most prevalent, along with various clastic rocks [17]. A series of tectonic movements since the Late Triassic has given rise to folded mountain formations, thereby establishing conditions that are highly conducive to rockfall development. Furthermore, coal seams in Guizhou Province are predominantly found within the strata of the Permian Liingshan and Longtan Formations. The rock types in these formations mainly include limestone, mudstone, and sandstone, interspersed with four to six layers of thin mud shale and other soft rocks. Prolonged underground mining activities have created mined-out areas beneath the mountains, which in turn lead to the formation of surface fissures, exacerbating the destruction of the rock mass and causing significant gradient deformation. Figure 2 shows the geological map of the study area. As a result, large-scale rockfalls frequently occur. This geological context highlights the urgent need for comprehensive studies on slope stability and risk management in the region.  
Various geological disasters occur in Guizhou every year. According to the Natural Resources Bureau of Guizhou Province statistics, by the end of 2021, there were  
Figure 1: The geographic location (**a**) of the study area (**b**) mountain elevations.  
Figure 2: The geological map of the study area.  
28,221 potential geological disasters, including 4812 landslides, 3091 rockfalls, 114 mudslides, and 1377 unstable slopes. According to the statistics of the Guizhou Ministry of Transportation and Communications, by the end of 2021, the length of the roads in Guizhou Province was 188,797.1 km, of which the length of highways was 8368 km. Figure 3 shows some of the rockfall accidents along roads in Guizhou Province. Once a rockfall accident occurs, it will cause traffic congestion in the study area and will even cause many personnel and property losses. Therefore, it is of great significance to evaluate the risk of road networks in the study area and to provide guidance to local governments for their management.